Insulin glargine: a review of its therapeutic use as a long-acting agent for the management of type 1 and 2 diabetes mellitus

Insulin glargine is a recombinant human insulin analogue produced by DNA technology using a nonpathogenic strain of Escherichia coli. Two modifications of human insulin result in a stable molecule which is soluble in slightly acidic conditions (pH 4.0) and precipitates in the neutral pH of subcutaneous tissue. Because of these properties, absorption of insulin glargine is delayed and the analogue provides a fairly constant, basal insulin supply without peaks in plasma insulin levels for approximately 24 hours, similar to that achieved by a continuous subcutaneous insulin infusion. Insulin glargine is indicated as a once daily subcutaneous injection to provide basal glycaemic control in adults and children aged >6 years with type 1 diabetes mellitus and in adults with type 2 diabetes mellitus. Fasting plasma glucose and fasting blood glucose levels generally improved to a greater extent in patients with type 1 diabetes mellitus receiving insulin glargine than patients who administered Neutral Protamine Hagedorn (NPH) insulin. In patients with type 1 or 2 disease, glycosylated haemoglobin levels were slightly reduced and to a similar extent with insulin glargine and NPH insulin. Most clinical trials in patients with type 1 or 2 diabetes mellitus demonstrated a lower incidence of hypoglycaemia, especially nocturnal hypoglycaemia, compared with NPH insulin. One of the most common adverse events with insulin glargine treatment was injection site pain which, in some studies, occurred more frequently than in patients receiving NPH insulin. In all cases the symptoms were mild and treatment discontinuation was not required. Otherwise, the drug is well tolerated and does not appear to be immunogenic. CONCLUSIONS: Insulin glargine once a day provides basal control of glycaemia for approximately 24 hours without inducing peaks in plasma insulin levels in patients with type 1 or 2 diabetes mellitus. In long term, well designed trials insulin glargine once daily improved glycaemic control at least as effectively as NPH insulin given once or twice daily. The drug was well tolerated and in most studies the incidence of nocturnal hypoglycaemia was significantly less in patients treated with insulin glargine compared with patients receiving NPH insulin. Therefore, insulin glargine is likely to be a useful addition to the armamentarium of insulin therapy by establishing basal glycaemic control with once daily administration and a reduced risk of nocturnal hypoglycaemia.     

Defining the role of insulin lispro in the management of postprandial hyperglycaemia in patients with type 2 diabetes mellitus

The role of postprandial hyperglycaemia in contributing to the risk of both micro- and macrovascular complications in patients with diabetes mellitus is being increasingly recognized. In type 2 diabetes, there is a progressive shift in the relative contributions of postprandial and fasting hyperglycaemia to the overall glycaemic control as the disease progresses. For patients with fairly good glycaemic control (glycosylated haemoglobin [HbA(1c)] <8.5%), postprandial hyperglycaemia makes a relatively greater contribution to the overall glycaemic load than fasting hyperglycaemia, but in patients with poorer control, the relative contribution of the two states to the overall glycaemic load is reversed. This finding, coupled with epidemiological evidence that elevated postprandial glucose concentration is an independent risk factor for cardiovascular disease (CVD), and is associated with a greater CVD risk than elevated fasting glucose, points to the need to monitor and target postprandial glucose, as well as fasting glucose and HbA(1c) levels, when optimizing insulin therapy for patients with type 2 diabetes. When insulin therapy becomes necessary in patients with type 2 diabetes who can no longer be controlled with oral antihyperglycaemic therapy, use of short-acting insulin analogues with a rapid onset of action and capable of controlling postprandial glycaemic excursions when injected immediately before a meal, has advantages over regular human insulin in that they provide a more favourable time-action profile that mimics normal physiological insulin secretion. Among the available rapid-acting insulin analogues, insulin lispro has been shown to reduce postprandial glucose concentrations to a significantly greater degree than regular human insulin in patients with type 2 diabetes. Moreover, premixed combinations of insulin lispro with the longer acting analogue neutral insulin lispro protamine suspension in 25% : 75% or 50% : 50% combinations are significantly more effective in lowering postprandial blood glucose concentrations than premixed regular human insulin plus neutral protamine Hagedorn (NPH) 30% : 70%. The premixed insulin lispro combinations offer the advantage of fewer daily injections than intensive insulin therapy, and the convenience of not having to mix insulin preparations manually. Although it has yet to be conclusively established that targeting postprandial hyperglycaemia reduces CVD risk, the potential benefits of improved postprandial and interprandial hyperglycaemia favour the use of newer insulin analogues, such as insulin lispro and insulin lispro mixes, over conventional insulin therapy, whenever insulin therapy becomes necessary in patients with type 2 diabetes.     

Insulin detemir: a review of its use in the management of type 1 and 2 diabetes mellitus

Insulin detemir (Levemir) is a soluble long-acting human insulin analogue acylated with a 14-carbon fatty acid. The fatty acid modification allows insulin detemir to reversibly bind to albumin, thereby providing slow absorption and a prolonged and consistent metabolic effect of up to 24 hours in patients with type 1 or type 2 diabetes mellitus. Insulin detemir has a more predictable, protracted and consistent effect on blood glucose than neutral protamine Hagedorn (NPH) insulin, with less intrapatient variability in glycaemic control, compared with NPH insulin or insulin glargine. Insulin detemir, administered once or twice daily, is at least as effective as NPH insulin in maintaining overall glycaemic control, with a similar or lower risk of hypoglycaemia, especially nocturnal hypoglycaemia, compared with NPH insulin in patients with type 1 or type 2 diabetes. Insulin detemir also provides the added clinical benefit of no appreciable bodyweight gain in patients with type 1 diabetes and less bodyweight gain than NPH insulin in patients with type 2 diabetes. Insulin detemir is, therefore, a promising new option for basal insulin therapy in patients with type 1 or 2 diabetes.     

Insulin lispro: a review of its use in the management of diabetes mellitus

Insulin lispro, alone (Humalog) or as premixture (Humalog Mix25 or Humalog Mix50) is indicated for the treatment of hyperglycaemia in diabetes mellitus in many countries worldwide. It is a recombinant human insulin analogue and, except for the transposition of two amino acids, is identical to endogenous human insulin. Insulin lispro has a faster onset of action and shorter duration of activity than regular human insulin, and the time-action profile of insulin lispro mimics that of the physiological response of endogenous human insulin to food intake. In diabetic patients, from young children to the elderly, it has demonstrated postprandial blood glucose control similar to or better than that achieved with regular human insulin, without an increased risk of hypoglycaemia. In some trials, the risk of hypoglycaemia, including nocturnal episodes, was less in insulin lispro recipients than in regular human insulin recipients. Insulin lispro alone, or as a premixture with the longer-acting insulin neutral protamine lispro, can be administered immediately before or after meals. This convenient and flexible injection schedule may enable patients, including those with a non-routine lifestyle or unpredictable eating or exercising habits, to achieve the tight glycaemic control required to minimise long-term complications of diabetes and contributes to patient satisfaction with treatment.     

The use of sulphonylureas in the elderly

Type 2 diabetes mellitus is a heterogeneous disorder characterised by defects in insulin secretion as well as reduced insulin action. During aging, glucose intolerance will gradually develop, and this is manifested primarily by an increase in the postprandial blood glucose response while fasting blood glucose levels are often less elevated. Abnormal beta-cell secretion of insulin is a main feature of this. Treatment of elderly patients with type 2 diabetes mellitus focuses on reduction of (hyperglycaemic) complaints and prevention of the development or progression of secondary complications. Although regular physical activity and dietary measures, aiming at bodyweight normalisation, are the cornerstones of therapy, pharmacological treatment with oral blood glucose lowering-agents often proves necessary to control the hyperglycaemia. In the United Kingdom Prospective Diabetes Study (UKPDS) it was clearly shown that patients with type 2 diabetes mellitus who were intensively treated with oral blood glucose-lowering agents or insulin developed less microvascular complications. The question whether achievement of strict metabolic control is also of benefit in elderly patients, is still unanswered. Sulphonylureas are drugs which stimulate insulin secretion by enhancing the release of insulin from the pancreatic beta-cells without an effect on insulin synthesis. They are frequently used in the treatment of type 2 diabetes mellitus, and several preparations are available. In general, there are no major differences in effectiveness between the various sulphonylureas. Long term treatment with sulphonylureas will decrease fasting and postprandial plasma glucose levels by 3 to 5 mmol/L, and glycosylated haemoglobin by 20%. However, after its initial decline, plasma glucose level will often go up slightly during the following months to years. Sulphonylureas are usually well tolerated. Hypoglycaemia is the most frequently occurring adverse effect, which may be very serious and damaging in the elderly. It has been associated primarily with long-acting sulphonylureas, like chlorpropamide and glibenclamide (glyburide). Hypoglycaemic episodes may trigger serious events like myocardial infarction or stroke. Therefore, shorter-acting compounds like tolbutamide and gliclazide have been relatively well tolerated and appear to be the best choice to treat elderly patients. It is advisable to start with a low dose and increase the dose, when needed, in small steps. The efficacy of sulphonylureas is much greater when they are taken before a meal. Because of the fact that type 2 diabetes mellitus is a progressive disease, and residual beta-cell function decreases with time, insulin therapy may ultimately be warranted in a significant number of patients.     

Defining the role of insulin detemir in Basal insulin therapy

Insulin detemir is a novel long-acting insulin analogue with a unique mechanism underlying its prolonged duration of action. Unlike neutral protamine Hagedorn (NPH) insulin (insulin suspension isophane) and insulin glargine, which precipitate after administration, insulin detemir remains soluble after it is injected. The prolonged duration of action of insulin detemir is a result of the ability to self-associate into hexamers and dihexamers, and to bind reversibly to albumin. This mechanism of protraction provides a more prolonged, consistent and predictable glycaemic effect in patients with type 1 or type 2 diabetes mellitus compared with NPH insulin. Clinical studies have demonstrated that insulin detemir administered once or twice daily is at least as effective as NPH insulin and insulin glargine in achieving glycaemic control. Most trials have also shown that insulin detemir exhibits less intrapatient variability in glycaemic control compared with NPH insulin and insulin glargine. One of the benefits of insulin detemir is its favourable effect on bodyweight. Insulin detemir has shown weight neutrality in patients with type 1 diabetes and is associated with less weight gain than NPH insulin in clinical studies. Patients with type 2 diabetes using insulin detemir gain less weight than patients using NPH insulin and insulin glargine. In addition, a reduced risk of hypoglycaemia, particularly nocturnal hypoglycaemia, has been reported with insulin detemir compared with NPH insulin in patients with type 1 and type 2 diabetes. A reduced risk of major and nocturnal hypoglycaemia compared with insulin glargine in patients with type 1 diabetes has also been observed. Together, these data indicate that insulin detemir is a valuable new option for basal insulin therapy in patients with type 1 or type 2 diabetes.     

Insulin glargine

Insulin glargine is an extended-action biosynthetic human insulin. It precipitates in the neutral environment of subcutaneous tissue and is thus gradually absorbed into the bloodstream. The addition of small amounts of zinc to the formulation further delays absorption. In small euglycaemic clamp studies, the onset of action of insulin glargine was shown to be later, the duration of action longer and the time-action profile flatter than that of Neutral Protamine Hagedorn (NPH) insulin in patients with type 1 diabetes mellitus and healthy volunteers. Four large clinical trials of up to 28 weeks' duration have shown that a single bedtime dose of insulin glargine, in combination with preprandial short-acting insulin, is as effective or more effective than once or twice daily NPH plus short-acting insulin in improving glycaemic control in patients with type 1 diabetes mellitus. In 3 large comparative trials, insulin glargine decreased glycosylated haemoglobin and/or fasting blood glucose levels to a similar extent to that seen with NPH insulin in patients with insulin-dependent or non-insulin-dependent type 2 diabetes mellitus, either as monotherapy or in combination with oral hypoglycaemic agents. Insulin glargine appears to be well tolerated. A lower incidence of hypoglycaemia, especially at night, was reported in most trials with insulin glargine when compared with NPH insulin.     

Clinical review of glimepiride

This article reviews the pharmacological and clinical aspects of glimepiride, the latest second-generation sulfonylurea for treatment of Type 2 diabetes mellitus (DM). Glimepiride therapy ameliorates the relative insulin secretory deficit found in most patients with Type 2 DM. It is a direct insulin secretagogue; indirectly, it also increases insulin secretion in response to fuels such as glucose. Its action to augment insulin secretion requires binding to a high affinity sulfonylurea receptor, which results in closure of ATP-sensitive potassium channels in the β-cells of the pancreas. The question has been raised whether insulin secretagogues by acting on vascular or myocardial potassium channels may prevent ischaemic preconditioning, a physiological adaptation that could affect the outcome of coronary heart disease, but there is evidence against this concern being applicable to glimepiride. Glimepiride’s antihyperglycaemic efficacy is equal to other secretagogues. It has pharmacokinetic properties that make it less prone to cause hypoglycaemia in renal dysfunction than some other insulin secretagogues, particularly glyburide (also known as glibenclamide in Europe). Its convenient once daily dosing may enhance compliance for diabetic patients who often also require medications for other co-morbid conditions, such as hypertension, hyperlipidaemia and cardiac disease. Glimepiride is approved for monotherapy, for combination with metformin and with insulin. Clinically, its reduced risk of hypoglycaemia makes it preferable to some other insulin secretagogues when attempting to achieve recommended glycaemic control (haemoglobin A_1c (HgbA_1c) 7%). Using suppertime neutral protamine Hagedorn (NPH) and regular insulin with morning glimepiride in overweight diabetic patients achieves glycaemic goals more quickly than insulin alone and with lower insulin doses.     

Clinical review of glimepiride

This article reviews the pharmacological and clinical aspects of glimepiride, the latest second-generation sulfonylurea for treatment of Type 2 diabetes mellitus (DM). Glimepiride therapy ameliorates the relative insulin secretory deficit found in most patients with Type 2 DM. It is a direct insulin secretagogue; indirectly, it also increases insulin secretion in response to fuels such as glucose. Its action to augment insulin secretion requires binding to a high affinity sulfonylurea receptor, which results in closure of ATP-sensitive potassium channels in the beta-cells of the pancreas. The question has been raised whether insulin secretagogues by acting on vascular or myocardial potassium channels may prevent ischaemic preconditioning, a physiological adaptation that could affect the outcome of coronary heart disease, but there is evidence against this concern being applicable to glimepiride. Glimepiride's antihyperglycaemic efficacy is equal to other secretagogues. It has pharmacokinetic properties that make it less prone to cause hypoglycaemia in renal dysfunction than some other insulin secretagogues, particularly glyburide (also known as glibenclamide in Europe). Its convenient once daily dosing may enhance compliance for diabetic patients who often also require medications for other co-morbid conditions, such as hypertension, hyperlipidaemia and cardiac disease. Glimepiride is approved for monotherapy, for combination with metformin and with insulin. Clinically, its reduced risk of hypoglycaemia makes it preferable to some other insulin secretagogues when attempting to achieve recommended glycaemic control (haemoglobin A(1c) (HgbA(1c)) 7%). Using suppertime neutral protamine Hagedorn (NPH) and regular insulin with morning glimepiride in overweight diabetic patients achieves glycaemic goals more quickly than insulin alone and with lower insulin doses.     

New insulin analogues and routes of delivery: pharmacodynamic and clinical considerations

Analogues of human insulin have been developed to more closely replicate the physiology of meal-related and basal insulin secretion. Three rapid-acting analogues and two basal analogues are available for clinical use. Insulin aspart and insulin lispro have nearly identical pharmacokinetic and pharmacodynamic profiles and provide better postprandial glucose control and less hypoglycaemia (primarily nocturnal and severe hypoglycaemia in type 1 diabetes mellitus) than regular insulin. Insulin glulisine is a new rapid-acting analogue and has characteristics nearly identical to those of its predecessors. Insulin glargine was the first basal analogue approved for clinical use and has shown better fasting glucose control and less risk of hypoglycaemia than conventional human neutral protamine Hagedorn (NPH) insulin. More recent studies have indicated that insulin glargine may not be truly 'peakless' at higher doses and that the adjustment of dose timing and frequency may have favourable effects on the risk of hypoglycaemia and the duration of the effect. Insulin detemir is a new basal insulin analogue with superiority to NPH insulin similar to that demonstrated by insulin glargine, though its duration of action appears to be shorter. The intraindividual variability in the response to a given dose is lower for insulin detemir than for both NPH insulin and insulin glargine. The clinical significance of this finding is not clear, though it may contribute to the lower rate of hypoglycaemia seen with insulin detemir. A number of 'alternative routes' of insulin administration have been studied, the most promising of which has been the pulmonary route. The time-action profile of inhaled insulins is generally characterized by a rapid onset of action similar to those of rapid-acting analogues and a slightly protracted duration of action similar to that of regular insulin. Inhaled insulin is similar to regular insulin with respect to efficacy and safety, though small reversible changes in pulmonary function have been noted. For technical and practical reasons, other alternative routes have generally not met with clinical success.     

Insulin glargine: an updated review of its use in the management of diabetes mellitus

Insulin glargine is a human insulin analogue prepared by recombinant DNA technology. Modification of the human insulin molecule at position A21 and at the C-terminus of the B-chain results in the formation of a stable compound that is soluble at pH 4.0, but forms amorphous microprecipitates in subcutaneous tissue from which small amounts of insulin glargine are gradually released. The plasma concentration versus time profile of insulin glargine is therefore relatively constant in relation to conventional human insulins, with no pronounced peak over 24 hours. This allows once-daily administration as basal therapy. Early randomised trials with insulin glargine generally showed greater reductions in fasting blood or plasma glucose levels and a reduced frequency of nocturnal hypoglycaemia relative to neutral protamine Hagedorn (NPH) insulin in patients with type 1 diabetes mellitus. In addition to this basal therapy, patients continued to use the regular mealtime insulin regimen to which they were accustomed. More recent data with insulin glargine have included evidence of improved glycaemic control, with improvements in satisfaction with treatment over NPH insulin. Furthermore, the time of day at which insulin glargine is injected has no clinically relevant effect on glycaemic control in these patients. There are also data from small, nonblind studies to suggest comparable glycaemic control with insulin glargine and continuous subcutaneous insulin infusion. Results from comparative studies and meta-analyses in individuals with type 2 diabetes show lower incidences of nocturnal hypoglycaemia with insulin glargine than with NPH insulin, with two studies showing a significantly greater improvement in glycosylated haemoglobin levels with insulin glargine than with NPH. Insulin glargine is well tolerated, and is not associated with greater immunogenicity or increases in bodyweight than NPH insulin. Long-term data show maintenance of glycaemic control with insulin glargine for up to 39 months in adults and children with type 1 and adults with type 2 diabetes. In conclusion, insulin glargine is an effective and well tolerated basal insulin therapy when given as a single daily subcutaneous injection to patients with diabetes, with benefits in terms of glycaemic control and reduced frequency of hypoglycaemia over regimens based on conventional basal insulins. Accumulating data and official recommendations show the suitability of insulin glargine for first-line use in selected patients with type 2 diabetes who require insulin treatment, as well as in patients with type 1 disease, and confirm its use in children and adolescents.     

Insulin glargine: a new long-acting insulin product.

The pharmacodynamics, pharmacokinetics, clinical efficacy, adverse effects, and dosage and administration of insulin glargine are reviewed. Current treatment regimens for patients with type 1 diabetes mellitus and some with type 2 are designed to provide a basal insulin level with intermittent preprandial insulin coverage. Insulin glargine precipitates after subcutaneous injection, slowing absorption. Insulin glargine is used as a basal insulin and exhibits a flat pharmacokinetic profile, with a duration of action of at least 24 hours. Hypoglycemia is the most commonly reported adverse effect, especially within the first four weeks after a switch to insulin glargine. Insulin glargine should not be mixed with any other insulin product and should be administered with a syringe that has not been used for other insulin products or other medications. Insulin glargine is administered once daily at bedtime. Patients previously receiving twice-daily isophane insulin (NPH) should receive an insulin glargine dosage 20% less than the total daily dose of NPH insulin. Clinical trials did not consistently show improvements in hemoglobin A1c levels when patients with type 1 diabetes mellitus were switched from NPH insulin once or twice daily to insulin glargine. Insulin glargine should be considered for patients who continue to have elevated morning blood glucose levels and problems with nocturnal hypoglycemia despite receiving NPH insulin at bedtime. In patients with type 2 diabetes mellitus, insulin glargine significantly improved glycemic control compared with once-daily NPH insulin, but not when it was compared with combined treatment with once- or twice-daily NPH insulin. Clinical trials assessing progression of retinopathy and nephropathy and comparing insulin glargine therapy with continuous subcutaneous insulin infusion therapy are needed to more clearly determine insulin glargine's role. Insulin glargine is a new long-acting formulation that can provide prolonged basal glucose control in patients with diabetes mellitus.     

Management of type 2 diabetes mellitus in the elderly: special considerations

The principles of managing type 2 diabetes mellitus in the elderly are no different from those in younger patients, but the priorities and therapeutic strategies need to be cautiously individualised. The objectives of treatment are to improve glycaemic control in a stepwise approach that involves nonpharmacological methods including diet and exercise, and pharmacological therapy including mixtures of oral antihyperglycaemic agents alone or in combination with insulin. Although the goals of treatment may be the same for elderly and younger patients, certain aspects of type 2 diabetes in the elderly require special consideration. Treatment decisions are influenced by age and life expectancy, comorbid conditions and severity of the vascular complications. Adherence to dietary therapy, physical activity, and medication regimens may be compromised by comorbid conditions and psychosocial limitations. Drug-induced hypoglycaemia has been the main consideration and the most serious potential complication. In addition, the long term macrovascular and microvascular complications of type 2 diabetes are a source of significant morbidity and mortality. Indeed, vascular and neuropathic complications are already present at the time of diagnosis in a significant number of patients, and the impact of improved diabetes control depends on the age and life expectancy of the patient. Age-related changes in pharmacokinetics and the potential for adverse effects and drug interactions should also be considered when choosing appropriate pharmacological therapy. In general, a conservative and stepwise approach to the treatment of the elderly patient with type 2 diabetes is suggested; treatment may be initiated with monotherapy, followed by early intervention with a combination of oral agents including a sulphonylurea as a foundation insulin secretagogue in addition to a supplemental insulin sensitiser. Insulin therapy is eventually required if significant hyperglycaemia [glycosylated haemoglobin (HbA1c) >8%] persists despite oral combination therapy. Combination therapy with evening insulin and a long-acting sulphonylurea such as glimepiride is an effective strategy to improve hyperglycaemia in the elderly patient with type 2 diabetes in whom polypharmacy with oral agents is unsuccessful. In addition, such a regimen is simple to follow for the patient who may not be able to adhere to a more complicated insulin regimen. Hyperglycaemia in the elderly can be managed well with practical intervention and a straightforward treatment plan to enhance compliance. Optimal glycaemic control should be possible for every patient if treatment is individualised; however, strict glycaemic control may not be achievable in all patients or even desirable in many elderly patients.     

Repaglinide: a review of its therapeutic use in type 2 diabetes mellitus

Repaglinide, a carbamoylmethyl benzoic acid derivative, is the first of a new class of oral antidiabetic agents designed to normalise postprandial glucose excursions in patients with type 2 diabetes mellitus. Like the sulphonylureas, repaglinide reduces blood glucose by stimulating insulin release from pancreatic beta-cells, but differs from these and other antidiabetic agents in its structure, binding profile, duration of action and mode of excretion. In clinical trials of up to 1-year's duration, repaglinide maintained or improved glycaemic control in patients with type 2 diabetes mellitus. In comparative, 1-year, double-blind, randomised trials (n = 256 to 544), patients receiving repaglinide (0.5 to 4mg before 3 daily meals) achieved similar glycaemic control to that in patients receiving glibenclamide (glyburide) < or = 15 mg/day and greater control than patients receiving glipizide < or = 15 mg/day. Changes from baseline in glycosylated haemoglobin and fasting blood glucose levels were similar between patients receiving repaglinide and glibenclamide in all studies; however, repaglinide was slightly better than glibenclamide in reducing postprandial blood glucose in I short term study (n = 192). Patients can vary their meal timetable with repaglinide: the glucose-lowering efficacy of repaglinide was similar for patients consuming 2, 3 or 4 meals a day. Repaglinide showed additive effects when used in combination with other oral antidiabetic agents including metformin, troglitazone, rosiglitazone and pioglitazone, and intermediate-acting insulin (NPH) given at bedtime. In 1-year trials, the most common adverse events reported in repaglinide recipients (n = 1,228) were hypoglycaemia (16%), upper respiratory tract infection (10%), rhinitis (7%), bronchitis (6%) and headache (9%). The overall incidence of hypoglycaemia was similar to that recorded in patients receiving glibenclamide, glipizide or gliclazide (n = 597) [18%]; however, the incidence of serious hypoglycaemia appears to be slightly higher in sulphonylurea recipients. Unlike glibenclamide, the risk of hypoglycaemia in patients receiving repaglinide was not increased when a meal was missed in 1 trial. In conclusion, repaglinide is a useful addition to the other currently available treatments for type 2 diabetes mellitus. Preprandial repaglinide has displayed antihyperglycaemic efficacy at least equal to that of various sulphonylureas and is associated with a reduced risk of serious hypoglycaemia. It is well tolerated in a wide range of patients, including the elderly, even if a meal is missed. Furthermore, glycaemic control is improved when repaglinide is used in combination with metformin. Thus, repaglinide should be considered for use in any patient with type 2 diabetes mellitus whose blood glucose cannot be controlled by diet or exercise alone, or as an adjunct in patients whose glucose levels are inadequately controlled on metformin alone.     

Exenatide

Exenatide is the first in a new class of compounds, which possess similar activity to the naturally-occurring hormone glucagon-like peptide-1 (GLP-1). It mirrors many of the effects of GLP-1, improving glycaemic control through a combination of mechanisms, which include glucose-dependent stimulation of insulin secretion, suppression of glucagon secretion, slowing of gastric emptying and reduced appetite. Phase III clinical trials showed exenatide therapy for 30 weeks significantly reduced glycated haemoglobin, and fasting and postprandial plasma glucose compared with baseline when added to metformin and sulfonylureas or a combination of the two, with an average weight loss of approximately 2 kg. Exenatide can also be used in combination with thiazolidinediones and may be an alternative to insulin in patients requiring additional therapy. In patients with established Type 2 diabetes, control of both glycaemia and body weight are important to minimise the risk of future diabetes complications. Open-label extensions from these pivotal trials demonstrate that patients treated with exenatide for < or = 3 years sustained the reductions in glycaemic control achieved at 30 weeks and had a progressive reduction in body weight. Exenatide is generally well tolerated; nausea is the most commonly reported side effect, but can be significantly reduced when a target dose of exenatide is achieved in patients with gradual dose titration. Hypoglycaemia has been encountered in clinical trials of exenatide, especially on initiation of therapy with sulfonylureas (not with metformin). Exenatide may enable patients with Type 2 diabetes to improve glycaemic control and reduce or eliminate the risk of hypoglycaemia and weight gain.     

Clinical pharmacokinetics of nateglinide: a rapidly-absorbed, short-acting insulinotropic agent

The prevalence and medical and economic impact of type 2 diabetes mellitus is increasing in Western societies. New agents have been developed that act primarily to reduce postprandial glucose excursions, which may be of particular significance now that postprandial glucose excursions are known to be correlated with cardiovascular morbidity and mortality. Nateglinide is a phenylalanine derivative that blocks K+ channels in pancreatic beta-cells, facilitating insulin secretion. Nateglinide sensitises beta-cells to ambient glucose, reducing the glucose concentration needed to stimulate insulin secretion. The pharmacokinetics of nateglinide are characterised by rapid absorption and elimination, with good (73%) bioavailability. Nateglinide is more rapidly absorbed when given 0-30 minutes prior to meal ingestion than if given during the meal. Nateglinide is extensively metabolised, primarily by cytochrome P450 2C9, and eliminated primarily by the kidney. Nateglinide pharmacokinetics are linear over the dose range 60-240 mg. No significant pharmacokinetic alterations occur in renally impaired patients, in the elderly, or in mildly hepatically impaired patients. Nateglinide administered prior to meals stimulates rapid, short-lived insulin secretion in a dose-dependent manner, thus decreasing mealtime plasma glucose excursions. Its effects on insulin secretion are synergistic with those of a meal. With increasing nateglinide doses, the risk of hypoglycaemia also increases, but its incidence is low. Even if a meal is missed, and the patient skips the dose of nateglinide (as recommended in the event of a missed meal), the incidence of subsequent hypoglycaemia remains low compared with long-acting agents. The postprandial insulinotropic effects of nateglinide are more rapid than those of repaglinide and more rapid and greater than those of glibenclamide (glyburide), while producing less prolonged insulin exposure and less risk of delayed hypoglycaemia. Further investigation is required to determine if nateglinide inhibition of postprandial glucose excursions will help to prevent diabetic complications or preserve pancreatic beta-cell function.     

A review of clinical experience with the prandial glucose regulator, repaglinide, in the treatment of type 2 diabetes

Repaglinide is a novel insulin secretagogue that was developed as a prandial glucose regulator for the treatment of people with Type 2 diabetes mellitus. It is used flexibly, taken prior to meals, in order to limit subsequent postprandial blood glucose excursions as well as the dependent basal blood glucose concentration. In theory, the pharmacological profile of repaglinide is well suited for this role. Taken at mealtimes, its relatively rapid-onset and short-duration of action counteract a fundamental pathophysiological aspect of this disease: attenuation of the prandial insulin response. The predominantly hepatic elimination profile and a lack of drug-drug interactions with repaglinide are also properties well suited for patients with Type 2 diabetes. Importantly, the pharmacokinetic properties of repaglinide, are expected to reduce the risk of hypoglycaemia in comparison to the conventional insulin secretagogues (sulphonylureas). A reduced risk of hypoglycaemia carries the advantage that patients are not obliged to consume meals at regular intervals supplemented by snacks, so caloric restriction is feasible and lifestyle not compromised. These theoretical advantages have now been largely borne-out by clinical studies and empirical experience. Placebo-controlled studies have consistently demonstrated the antidiabetic efficacy of repaglinide, with improvements having been shown in all indicators of glycaemic control. Double-blind, active-comparator studies have shown repaglinide to have an antidiabetic efficacy that is at least equivalent to sulphonylureas, even when food intake and dosing intervals were controlled according to the requirements of sulphonylureas. Pooled data from these studies have shown that the risk of severe hypoglycaemia is reduced by 60% (p = 0.03) when repaglinide is used in preference to sulphonylureas. There is also evidence that the blood glucose threshold at which symptoms of hypoglycaemia are perceived by patients may be better preserved during treatment with repaglinide than with sulphonylureas. Studies examining flexible prandial dosing with repaglinide have shown that good glycaemic control and a low risk of hypoglycaemia are achievable goals that are independent of the meal (and, hence, dosing) pattern chosen by the patient. Furthermore, when used in this way, repaglinide has not been associated with weight gain. In combination therapy, repaglinide has been shown to act in synergy with both metformin and troglitazone. The possibility of a 'new' basal-bolus regimen combining repaglinide and exogenous (neutral protamine hagedorn) NPH insulin strategy has also been investigated.     

Insulin analogue therapy in pregnancies complicated by diabetes mellitus

Pregnancies complicated by diabetes mellitus (DM) include pregestational DM and gestational DM, defined as carbohydrate intolerance of variable severity first detected during pregnancy. DM leads to poor pregnancy outcome. The aim of treatment is to control maternal hyperglycaemia and to imitate postprandial insulin release. Rapid-acting insulin analogues are suitable therapeutic candidates, as they are able to reduce postprandial hyperglycaemia (predictive of adverse pregnancy outcome). There is no excess risk of adverse fetal or maternal outcomes when compared with regular insulin. Data suggest that rapid-acting insulin analogues do not transfer to human placenta. Because of the reduced risk of hypoglycaemia and improved postprandial and overall glucose control, insulin analogues could be considered the rapid-acting insulin choice during pregnancy.     

Insulin analogue therapy in pregnancies complicated by diabetes mellitus

Pregnancies complicated by diabetes mellitus (DM) include pregestational DM and gestational DM, defined as carbohydrate intolerance of variable severity first detected during pregnancy. DM leads to poor pregnancy outcome. The aim of treatment is to control maternal hyperglycaemia and to imitate postprandial insulin release. Rapid-acting insulin analogues are suitable therapeutic candidates, as they are able to reduce postprandial hyperglycaemia (predictive of adverse pregnancy outcome). There is no excess risk of adverse fetal or maternal outcomes when compared with regular insulin. Data suggest that rapid-acting insulin analogues do not transfer to human placenta. Because of the reduced risk of hypoglycaemia and improved postprandial and overall glucose control, insulin analogues could be considered the rapid-acting in-sulin choice during pregnancy.     

Glucose and low-density lipoprotein cholesterol lowering in elderly patients with type 2 diabetes: focus on combination therapy with colesevelam HCl

The prevalence of type 2 diabetes mellitus is high among the elderly population. Treatment of elderly patients with type 2 diabetes presents challenges because of co-morbidities and the potential increase in the risk of adverse effects. Hyperlipidaemia is also common in the elderly population. Glucose- and lipid-lowering treatment in elderly patients should be individualized on the basis of the patient's life expectancy, health status and cardiovascular risk factors, and evidence-based guideline recommendations. Because elderly patients often have impaired renal and hepatic function, careful considerations must be made when selecting appropriate glucose- and lipid-lowering therapy. There are a number of potential safety issues associated with various glucose- and lipid-lowering therapies that are relevant to elderly patients, including increased risk of heart failure exacerbations, weight loss, increased risk of hypoglycaemia, increased risk of myopathy, and contraindications of some agents in patients with hepatic or renal impairment. The bile acid sequestrant colesevelam HCl is unique compared with other glucose- and lipid-lowering therapies because it is the only product approved by the US Food and Drug Administration, as an adjunct to diet and exercise, to lower both glucose and low-density lipoprotein cholesterol (LDL-C) in adults with type 2 diabetes and primary hyperlipidaemia, respectively. Furthermore, colesevelam has been shown to have similar glucose- and lipid-lowering efficacy in patients aged <65 years and those aged ≥65 years. Colesevelam was not associated with weight gain, was associated with a low incidence of hypoglycaemia, and can be safely combined with a broad range of glucose-lowering agents (metformin, sulfonylureas and insulin) and lipid-lowering statins. Currently, colesevelam is available in tablet form and as a powder for oral suspension formulation; the latter may be of benefit to elderly patients with swallowing difficulties. As colesevelam has both glucose- and lipid-lowering effects, its use may reduce the drug burden in elderly patients receiving multiple agents for glucose and lipid lowering. Colesevelam may be a valuable treatment option as an add-on to existing glucose- and/or lipid-lowering therapy to help improve haemoglobin A(1c) and to lower LDL-C levels in elderly patients with type 2 diabetes and primary hyperlipidaemia.