Insulin injection in the fetal rat: accelerated intrauterine growth and altered fetal and neonatal glucose homeostasis

Fetal hyperinsulinemia is a well-known correlate of accelerated fetal growth; the consequences of fetal hyperinsulinemia upon fetal and neonatal glucoregulation are less well understood. We injected rat fetuses of a litter on day 18 of gestation with either 5 units of long acting insulin (I) or 154 mmol/L NaCl. Twelve hours after injection, the wet and dry mass of total body and liver of I fetuses significantly exceeded that of controls. At birth (day 21.5), newborn I pups weighed 5.86 +/- .08 g, and controls, 5.48 +/- .05 g, (P less than .001). On day 18, within one hour of injection, fetal plasma insulin concentrations were significantly elevated and remained so for 24 hours. Mothers of I fetuses had significant elevations of plasma insulin at 1, 3, and 6 hours, and they developed transient hypoglycemia. Plasma glucose concentrations in I fetuses were significantly diminished at 1, 3, and 6 hours and then achieved control levels by 12 hours. Fetal hypoglycemia resulted from an apparent direct effect of insulin upon fetal tissue and from the maternal hypoglycemia. Hypoglycemic I fetuses demonstrated a sluggish alpha-cell response; they failed to increase plasma glucagon one hour after insulin injection. Values were significantly increased three hours after injection. At birth, I pups became hypoglycemic relative to controls. This was, in part, due to their significantly elevated plasma insulin concentrations at 120 and 240 minutes (120 minutes, 43.8 +/- 8 v 17.5 +/- 6 microU/mL, P less than .001). Plasma glucagon was significantly increased in I pups at 240 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Improvement of glucose tolerance by nateglinide occurs through enhancement of early phase insulin secretion.

Nateglinide is a new, fast-onset, short-acting hypoglycemic agent, which increases early phase insulin secretion and the total amount of insulin secreted. However, it is not clear which of these effects contribute more to the decrease in postprandial plasma glucose (PG). To further clarify the pharmacologic actions of nateglinide, we investigated the changes in PG and insulin levels during meal tolerance tests with and without nateglinide. Subjects were 10 newly diagnosed and untreated inpatients with type 2 diabetes. After diet and exercise therapy for 1 week, nateglinide at 270 mg divided 3 times a day, was started. Meal tolerance tests were performed before (baseline) and after a single nateglinide administration (day 1), after 7 days of repeated administration (day 7), and after cessation of nateglinide on day 8. Mean fasting PG was 146 +/- 6 mg/dl (mean +/- SEM) at baseline and 130 +/- 6 mg/dL on day 7 (P =.0004). The 2-hour postprandial PG level was 226 +/- 10 mg/dL at baseline, 145 +/- 11 mg/dL on day 1 (P =.0008), and 190 +/- 15 mg/dL on day 8 (P =.08, baseline; P =.01, day 7). The mean fasting insulin level was 5.4 +/- 1.0 microU/mL at baseline and did not change significantly during the study. The 30-minute postprandial insulin level was 14.4 +/- 1.9 microU/mL at baseline, 39.5 +/- 4.5 microU/mL on day 1 (P =.0004), and 23.6 +/- 3.6 microU/mL on day 8 (P =.045, baseline; P =.010, day 7). The total insulin amount, in terms of area under the curve (AUC. IRI), was 3.99 +/- 0.7 x 10(3) microU/mL. min at baseline, 5.47 +/- 0.8 microU/mL. min on day 1 (P =.029), and 6.01 +/- 1.9 microU/mL. min on day 8 (P =.047 v baseline). The early phase of insulin secretion, based on the ratio of delta IRI to delta PG from fasting to 30 minutes after a meal was 0.15 +/- 0.13 at baseline, 1.44 +/- 0.26 on day 1 (P =.0009) and 0.26 +/- 0.06 on day 8 (P =.05 v day 1). After cessation of nateglinide, the postprandial PG level increased immediately. Although early phase insulin secretion returned nearly to the baseline level, total insulin secretion remained at a high level. These results suggested that early phase insulin secretion contributes more than total insulin secretion to the improvement of postprandial hyperglycemia in type 2 diabetes.     

Elevated growth hormone levels and insulin resistance in patients with cirrhosis of the liver

Carbohydrate intolerance is frequently seen in patients with hepatic cirrhosis. To study the role of the counter regulatory hormones, glucagon, cortisol and growth hormone in this disease, these hormones were measured in 11 patients with hepatic cirrhosis and six controls during a 4-hour oral glucose tolerance test (OGTT) and in five normal and cirrhotic subjects during steady-state plasma insulin and glucose concentrations (SSPGI) achieved with the euglycemic clamp technique. Fasting plasma glucose was 103 +/- 4.3 mg/dl in cirrhotics and 88 +/- 3.3 mg/dl in controls (p less than 0.001). Immunoreactive insulin (IRI) was 24.3 microU/ml in cirrhotics and 12.7 +/- 2.2 microU/ml in controls (p less than 0.001); immunoreactive glucagon (IRG) was 263 +/- 30 pg/ml in cirrhotics and 122 +/- 17.5 pg/ml in controls (p less than 0.001); serum growth hormone (GH) was 4.4 +/- 0.9 ng/ml in cirrhotics and 0.5 +/- 0.1 ng/ml in controls (p less than 0.001). During OGTT, the 2-hour glucose concentration was 201 +/- 9.7 mg/dl in cirrhotic subjects and 147 +/- 10.0 mg/dl in controls (p less than 0.001). IRG levels were suppressed by 20% of basal values in patients with cirrhosis, while controls showed 10% suppression after an oral glucose load. At 60 minutes, the serum GH was 14.7 +/- 3.9 ng/ml in cirrhotics and 0.3 +/- 0.1 ng/ml in controls (p less than 0.001). The normal suppressive effect of hyperglycemia on GH secretion in controls was sharply contrasted by a paradoxical elevation of serum GH in the cirrhotic group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Exercise-induced hypoglycaemia and subcutaneous insulin infusion

To assess whether exercise-induced hypoglycaemia could be prevented by interruption of insulin infusion (3 h) we studied diabetic patients treated with continuous subcutaneous insulin infusion (CSII). The studies were performed in 7 insulin-dependent diabetics (aged 31.4 +/- 4.8 (mean +/- SD) years, duration of diabetes 16.9 +/- 5.4 years), after an overnight fast and in the afternoon, 4 h after the last pre-meal bolus injection (exercise and control period). Bicycle exercise (45 min at 60% of maximum oxygen consumption) was started 30 min after the insulin infusion was stopped. During exercise there was a more pronounced decline in blood glucose in the afternoon (2.2 +/- 0.3 mmol/l, mean +/- SEM) than in the morning (1.4 +/- 0.4 mmol/l) (p less than 0.01). This corresponded to higher mean levels of free insulin during exercise in the afternoon (20 +/- 4.5 mU/I vs 12.0 +/- 1.0 mU/l, in the morning). Interruption of insulin delivery for 3 h resulted in a moderate increase of blood glucose, a gradual decrease of free insulin, and a moderate increase in free fatty acids and beta-hydroxybutyrate. During exercise in the afternoon 3 diabetics suffered from symptomatic hypoglycaemia (BG less than 2.8 mmol/l). In contrast with most of the other patients they showed no decline of free insulin during exercise. Thus even after interruption of basal rate insulin infusion moderate postprandial exercise may lead to hypoglycaemia if there is relative hyperinsulinism.     

Stimulation of insulin secretion by a rapid intravenous calcium infusion in patients with beta-cell neoplasms of the pancreas

The effects of calcium on fasting plasma insulin and glucose levels were compared in 16 normal subjects and 11 patients with beta-cell neoplasms of the pancreas. Calcium was administered iv either as a rapid calcium infusion (RCI; 2 mg/kg in 1 min) or as a long calcium infusion (LCI; 12 mg/kg in 3 h). In normal subjects, the RCI produced a rise in mean plasma insulin from 11 +/- 1 (+/- SEM) microU/ml basally to a peak of 18 +/- 2 microU/ml (P less than 0.001). No consistent pattern of change in insulin levels occurred during the LCI, and plasma glucose levels did not change significantly with either test. In the patients with beta-cell neoplasms, the RCI resulted in a rapid increase in mean plasma insulin from 36 +/- 6 microU/ml to a peak level of 312 +/- 67 microU/ml (P less than 0.002). With the LCI, a more gradual rise in insulin from 35 +/- 11 to 92 +/- 36 microU/ml occurred (P less than 0.002). The mean increase in insulin in the patients with beta-cell neoplasms was significantly greater for the RCI than for the LCI (P less than 0.01). Pronounced increments in plasma insulin occurred in all 11 patients after the RCI, but in only 3 of 8 patients during the LCI. Plasma glucose levels declined significantly from 69 +/- 7 to 56 +/- 8 mg/dl during the RCI (P less than 0.05) and from 69 +/- 8 to 49 +/- 7 mg/dl during the LCI (P less than 0.005). Symptomatic hypoglycemia developed in 3 patients during the LCI but did not occur after the RCI. These data indicate that calcium is a more effective insulin secretagogue in patients with beta-cell neoplasms when administered as an RCI than as an LCI, and suggest that the RCI may be a useful test for the diagnosis of insulin-secreting tumors.     

Biphasic insulin aspart compared to biphasic human insulin reduces postprandial hyperlipidemia in patients with Type 2 diabetes.

BACKGROUND: Premixed insulin analogues reduce postprandial hyperglycemia in patients with Type 2 diabetes in comparison to premixed regular insulin. Insulin also plays an important role in the regulation of postprandial lipid metabolism. It is known that increased levels of postprandial insulin reduce postprandial hyperlipemia but, on the other hand, no information exists with regard to the possible effect of insulin analogues in comparison to human insulin. MATERIALS AND METHODS: 12 subjects (3 men; age 59 +/- 5 years; BMI 30.5 +/- 5.9 kg/m2, duration of diabetes 9 +/- 1 years, HbA1c 8.33 +/- 1.1 %) already on therapy with premixed insulin were treated either with biphasic human insulin (BHI30) or with biphasic insulin aspart (BIAsp30) (1.3 IU fast acting insulin/12 g KH) in the setting of a standardized test meal. Serum levels of glucose, insulin, C-peptide and triglycerides as well as retinylpalmitate in plasma and chylomicron remnants were determined before and up to 8 hours after the meal. RESULTS: As was to be expected, therapy with BIAsp30 reduced the maximum increase of postprandial glucose from 7.10 +/- 2.00 mmol/l to 5.27 +/- 1.83 mmo/l (p = 0.007) compared to BHI30 insulin. In the same way, the maximum increase of triglycerides (from 2.33 +/- 1.03 to 1.65 +/- 0.69 mmol/l, p = 0.014) was reduced. The AUC 0 - 8 for triglycerides was not significantly influenced (34.20 +/- 19.86 vs. 31.46 +/- 16.21 mmol x 8 h/l) but the incremental area over baseline (AOB 0 - 8) was significantly reduced from 8.02 +/- 4.35 to 6.12 +/- 3.94 mmol x 8 h/l (p = 0.024). CONCLUSIONS: Compared to conventional human premixed insulin the prandial therapy with biphasic insulin aspart results not only in an improvement of glucose tolerance but also in a significant reduction of postprandial hyperlipemia.     

Postprandial versus preprandial dosing of biphasic insulin aspart in elderly type 2 diabetes patients

Preprandial dosing (within 5 min before meal) and postprandial dosing (15-20 min after meal onset) of NovoLog Mix 70/30 (BIAsp 30, a biphasic formulation of insulin aspart, 30% soluble and 70% protamine-crystallized) were compared in elderly (> or =65 years) type 2 diabetes patients in this open-label, 12-week, crossover study. Ninety-three patients were treated with b.i.d. preprandial injections of BIAsp 30 during a 2-week run-in period and subsequently randomized to a 4-week treatment with either pre- or postprandial b.i.d. BIAsp 30, followed by crossover to the other regimen for 4 weeks. Mean plasma glucose values during a 4-h mealtest at the end of each treatment were similar for pre- and postprandial BIAsp 30 (153 +/- 58 mg/dl and 161 +/- 59 mg/dl, respectively, difference not significant). However, the mean blood glucose increment from self-measured blood glucose values was slightly but significantly greater after postprandial injection than after preprandial injection (treatment difference: 16.3mg/dl; 95% CI: [0.5, 29.3]). Fifty-six percent of patients reported a hypoglycemic episode; postprandial injection did not increase the incidence of hypoglycemia as compared to preprandial injection (113 episodes versus 125 episodes, respectively). For some elderly type 2 diabetes patients, postprandial injection of BIAsp 30 may be an acceptable alternative to standard preprandial injection.     

The effects of sucrose meal on insulin requirement in IDDM and its modulation by acarbose

The purpose of the present study was to evaluate the insulin requirement in response to sucrose meal in IDDM and its modulation by a disaccharidase inhibitor, Acarbose. After an overnight fast, the subjects (n = 9) were "hooked" to the artificial pancreas (Biostator) to maintain normoglycemia. Blood glucose and insulin requirement were recorded by the Biostator throughout the experiment. The patients were divided into two groups. In group I, five patients received increasing sucrose load (50, 75 and 100 g) with and without Acarbose 100 mg. After a 50 g sucrose meal with and without Acarbose, the peak postprandial (PP) blood glucose was 118 and 157 mg/dl and the insulin requirement was 3.9 and 7.8 units resulting in free plasma insulin peak of 34 and 59 microU/ml respectively. After a 75 g sucrose meal with and without Acarbose, the peak PC blood glucose was 134 and 166 mg/dl and the insulin requirement was 5.7 and 9.9 units resulting in free plasma insulin peak of 75 and 87 microU/ml. After a 100 g sucrose meal with and without Acarbose the peak PP blood glucose was 131 and 175 mg/dl and the insulin requirement was 6 and 12.8 units resulting in free plasma insulin peak of 50 and 69 microU/ml. In group II, four patients received increasing Acarbose dose with a fixed sucrose load (75 g). The PP blood glucose peaked at 161, 145, 120 and 102 mg/dl after 0, 50, 100, 200 mg of Acarbose respectively. The total insulin requirements were 12.9, 9.6, 4.3 and 3.1 units. The free plasma insulin was decreased by Acarbose treatment while plasma glucagon remained unaffected.(ABSTRACT TRUNCATED AT 250 WORDS)     

Glucose-stimulated insulin response in non-diabetic patients with lipoprotein lipase deficiency and hypertriglyceridemia

Elevations in plasma triglyceride (TG) and free fatty acid (FFA) concentrations are generally thought to play a role in the pathogenesis of insulin-resistant diabetes. The objective of this study was to investigate the relationship between hypertriglyceridemia and glucose-stimulated insulin responsiveness in non-diabetic patients. Forty subjects were divided into three BMI-matched groups as follows: one group consisted of 8 patients with a lipoprotein lipase (LPL) deficiency, another consisted of 12 patients with hypertriglyceridemia and a third consisted of 20 subjects with normal TG levels. In response to a 75 g oral glucose tolerance test, plasma insulin levels in the LPL-deficient subjects were higher (106+/-11 microU/ml) than those in the hypertriglyceridemic (69+/-16 microU/ml) and normolipidemic (29+/-3 microU/ml) subjects, at 30 min. On the other hand, their plasma glucose levels (127+/-6 mg/dl) were less than those seen in the normolipidemic group (165+/-9 mg/dl) after 90 min. Thus, LPL-deficient subjects with hypertriglyceridemia displayed an enhanced glucose-stimulated insulin response as well as lower blood glucose levels, the latter of which is not generally seen in those with hypertriglyceridemia and normolipidemia.     

Increased gastric inhibitory polypeptide is not reduced in patients with noninsulin-dependent diabetes mellitus treated with intense insulin therapy

Serum glucose and gastric inhibitory polypeptide (GIP) responses during mixed test meals and primed continuous infusion of insulin using the insulin clamp technique were studied in nine patients with noninsulin-dependent diabetes mellitus (NIDDM) before and after vigorous insulin treatment. Fasting serum glucose concentrations fell an average of 167 mg/dl (P less than 0.001), and there was a 67% reduction (P less than 0.001) in the postprandial glucose response. Mean hemoglobin A1c declined and paralleled the fall in serum glucose concentrations (9.2 +/- 0.5% to 5.9% +/- 0.3%; P less than 0.01). This improvement in glycemic control, however, was not associated with any appreciable change in GIP secretion. Basal and meal-stimulated serum GIP levels were not reduced after intense insulin therapy. Furthermore, hyperinsulinemia at physiological (100 microU/ml) and superphysiological (1000 microU/ml) levels failed to reduce GIP secretion before and after insulin therapy. Before insulin therapy, seven patients had elevated basal GIP levels and five had increased GIP levels after meals compared to values in nondiabetic subjects. Insulin administration did not alter these elevated GIP levels. These findings suggest that the increased meal-stimulated GIP secretion in some patients with NIDDM is not due to a failure of insulin feedback on GIP secretion.     

The physiological significance of the glucose intolerance of aging

Aging is associated with glucose intolerance, but its significance is unclear. We performed oral glucose tolerance tests and more physiologic meal tolerance tests in a group of 23 young adults, mean (+/- SE) age, 37 +/- 2 years and 17 elderly adults, mean age 69 +/- 1 years. The total glucose and insulin responses following the oral glucose load were increased by 24% and 127% respectively in the elderly compared with the young (24,524 +/- 1,080 vs. 19,734 +/- 702 mg/dl X min and 24,289 +/- 3,401 vs. 10,700 +/- 1,209 microU/ml X min). Following mixed meals, the total glucose response was 45,795 +/- 1,343 mg/dl X min in the young, compared with 50,998 +/- 1,850 mg/dl X min in the elderly (p less than .05) an 11% increase. Total insulin response was increased by 40% in the elderly (38,590 +/- 3,662 microU/ml X min) compared with the young (27,481 +/- 2,805 microU/ml X min) (p less than .05). We conclude that following the ingestion of more physiologic mixed meals, modest postprandial hyperglycemia and hyperinsulinemia can be demonstrated in elderly adults.     

Electrolyte disorders following massive insulin overdose in a patient with type 2 diabetes

We present a case of a 47-year-old man with Type 2 diabetes mellitus who attempted suicide with 2,100 U of insulin injected subcutaneously. Administration of dextrose intravenously was required to maintain the blood glucose concentration normally for 5 days. Moreover, hypokalemia, hypophosphatemia, and hypomagnesemia were also seen for 24 hours after insulin injection. The serum phosphorus and magnesium concentrations decreased to nadirs of 1.6 mg/dl and 1.6 mg/dl respectively 7 hours after insulin injection. Electrolyte disorders other than hypokalemia may be induced in hypoglycemic patients by massive insulin overdose.     

Increase in postprandial serum insulin levels in epileptic patients with valproic acid therapy

A significant weight gain and increase in serum leptin levels in the course of antiepileptic treatment with valproic acid (VPA) has been described in several clinical studies. With respect to the long treatment period in antiepileptic therapy, these side effects might increase insulin resistance and metabolic risk factors. We have studied clinical and laboratory effects of VPA treatment in a cohort of female patients (n = 22) and in patients treated with carbamazepine (CBZ) or lamotrigine monotherapy (n = 21). All study participants underwent an oral glucose tolerance test (OGTT) with 75 g glucose. Body mass index (BMI) in the VPA group was higher (28.1 +/- 3.6 kg/m(2)) than in the control group (23.9 +/- 3.7 kg/m(2)) (P <.039). While plasma glucose, serum leptin, insulin, and C-peptide levels did not differ significantly between the study groups in the fasting state, postprandial (pp) insulin and proinsulin levels were found to be significantly higher in the VPA than in the control group. In the course of the OGTT, serum insulin levels reached their peak values 1 hour postprandially with 68.8 +/- 10.0 microU/mL in the VPA group and 49.8 +/- 11.2 microU/mL in the control group (P <.042). After 2 hours, the corresponding serum insulin levels were 48.5 +/- 25.2 microU/mL and 34.1 +/- 17.2 microU/mL (P <.048) and the proinsulin levels 52.5 +/- 30.2 pmol/L and 29.5 +/- 12.0 pmol/L (P <.017). While BMI values in the non-VPA group showed a significant correlation only with the fasting values of insulin, proinsulin, and C-peptide, the BMI values of the VPA-treated group were also positively related to the 2-hour pp levels of insulin (R =.690; P <.001), proinsulin (R =.667; P <.001) and C-peptide (R =.502; P <.017). VPA is a fatty acid derivative, competes with free fatty acids (FFA) for albumin binding, and acts as a gamma aminobutyric acid (GABA)-ergic agonist, mechanisms, which are known to be involved in pancreatic beta-cell regulation and insulin secretion. Therefore, it might be suspected that VPA therapy is associated with increased glucose stimulated pancreatic secretion and thus a higher body weight in the VPA group.     

Effects of a somatostatin derivative (SMS 201-995) on postprandial hyperglycemia in insulin-dependent diabetics studied by means of a closed-loop device

We studied the effects of a premeal sc injection of an analog of somatostatin (SMS 201-995, Sandoz) on the postprandial glycemic excursions, insulin requirement and hormone profiles (GH, glucagon and C-peptide) in 8 IDDM patients (diabetes duration 14.0 +/- 6.5 yr, daily insulin requirement 36 +/- 6.4 U) maintained normoglycemic by connecting them to a closed-loop insulin infusion system (Betalike, Genoa). The morning of the test the patients were connected to the Betalike and their glucose levels stabilized for at least 4 h. At 13:00 h the study was begun with a sc injection of 50 micrograms of SMS 201-995 or placebo (randomly) and a standardized mixed meal (800 Kcal) was given. Blood samples were obtained 0, 15, 30, 60, 120 and 180 min after the injection. Each patient was tested both with SMS 201-995 and placebo. Postmeal glycemic peaks were decreased after SMS 201-995 (119.6 +/- 5.4 mg/dl vs 149.1 +/- 4.2; p less than 0.05) as well as insulin requirements (3.2 +/- 0.8 U vs 13.3 +/- 1.9; p less than 0.01) for the 180 min postprandial period. Similarly, glucagon level was reduced 30 min postprandially (24 +/- 6 pg/ml vs 59 +/- 24; p less than 0.05) and so GH level only 180 min after lunch (p less than 0.05). The premeal injection of SMS decreases postprandial glycemic excursions and the corresponding insulin requirement. The action of SMS 201-995 may be mainly mediated by the suppression of postprandial glucagon peak.     

Effect of a new long-acting somatostatin analogue (SMS 201-995) on glycemic and hormonal response to a mixed meal in acromegalic patients

We investigated in 6 acromegalic patients the acute effects on glucose tolerance and insulin secretion of a single sc injection of the somatostatin analogue SMS 201-995, performed 4 h before a mixed meal with xylose administration. Growth hormone levels decreased from 34.0 +/- 20.3 (mean +/- SE) to a minimum of 9.3 +/- 3.0 ng/ml, 3 1/2 h after the injection. A significant inhibition of insulin secretion was also noticed, with a fall from 25.3 +/- 6.4 to 6.3 +/- 2.3 microU/ml at 1 h, and a lower and delayed peak level after the mixed meal. However, the postprandial plasma glucose increase was not different from a control day, while plasma xylose levels were lower. Mean glucagon level after SMS 201-995 was lower than control value in 3 out of the 4 patients in whom it was determined. The decrease of serum growth hormone levels, together with partial glucagon inhibition and, more important, a slowing of intestinal absorptive processes, counterbalanced the inhibitory action of SMS 201-995 on insulin secretion, and no deterioration in carbohydrate tolerance could be demonstrated. However, before SMS 201-995 is employed in the management of acromegalic patients refractory to surgery and bromocriptine therapy, we need further observations of postprandial glycemic profiles during long-term therapy with multiple daily injections of the compound.     

Mechanisms of impaired acute insulin release in adult onset diabetes: studies with isoproterenol and secretin.

Previous work has suggested that impaired islet glucose recognition occurs in patients with adult onset diabetes, as acute insulin release is absent after iv glucose but present after beta adrenergic stimulation with isoproterenol (Iso). However, insulin responses to Iso were variably reduced as compared to normal in the diabetics. In order to evaluate the importance of the Iso dose, dose-response studies were performed in 9 diabetics (fasting plasma glucose greater than 150 mg/dl) and 10 age-matched controls. In both control subjects and diabetics, 0.5 microgram Iso produced no insulin response; 2 micrograms Iso produced an intermediate response; and 8 and 12 micrograms Iso produced a higher response. The insulin responses to the larger doses of Iso were lower in diabetics than control subjects (8 micrograms, 20 +/- 5 vs. 39 +/- 6 (P less than 0.025); 12 micrograms, 21 +/- 6 vs. 37 +/- 4 (P less than 0.05); means +/- SEM, microU/ml). Of 16 diabetics who received 12 micrograms Iso, 5 had insulin responses greater than 2 SD below the control mean, while others had responses that spanned the entire range of normal. Seven diabetics also were given iv secretin (150 U). Their insulin responses to secretin correlated with the responses to Iso (r = 0.83, P less than 0.02). Thus, patients with subnormal responses to Iso also had low secretion responses. The abnormalities of acute insulin secretion in diabetics can be explained by a lesion variably affecting islet membrane receptors; some patients may have glucose receptor damage, but intact responses to other stimuli, and others may have more widespread damage affecting beta-adrenergic and secretin responses as well. Alternatively, there may be heterogeneity in adult onset diabetes, as patients with low responses to all stimuli could have a qualitatively different lesion affecting insulin secretory capacity rather than membrane receptors.     

Managing diabetic surgical patients with glucose-free saline and insulin

Sixty-one people with glucose intolerance received a glucose-free solution during surgery. If their blood glucose levels rose above 200 mg/dl, they were given insulin intravenously, according to a rate algorithm reported elsewhere. None of the cases judged to be borderline required any insulin during their operations. Ten percent of the diabetics who were being treated with diet alone, and 40% of those using hypoglycemic agents or insulin, did require insulin. Insulin was delivered at an average rate of 2.1 +/- 5.2 U/h and controlled the serum glucose levels within a range of 132 +/- 32 mg/dl. This suggests that half of all diabetics undergoing surgery require only a glucose-free solution for fluid replacement to maintain their glucose levels below 200 mg/dl, and that insulin infusion is an appropriate means to control hyperglycemia during surgery.     

Insulin resistance in uraemic insulin-dependent diabetics. Effect of dialysis therapy as assessed by the artificial endocrine pancreas

Twenty-four hour insulin requirements were measured in 5 uraemic insulin-dependent diabetics using a glucose controlled insulin infusion system (artificial endocrine pancreas). All patients were studied twice: initially 14 (1-27) days before institution of dialysis treatment and again after a mean of 46 (21-98) days on chronic dialysis therapy. At near normal blood glucose level the daily insulin requirements decreased from 44.8 +/- 2.9 U pre-dialysis to 35.0 +/- 2.3 U post-dialysis (P less than 0.001). The reduction included the prandial as well as the basal requirements. Consistent with this, the mean plasma free insulin level was higher pre-dialysis than post-dialysis (42 +/- 12 microU/ml vs 31 +/- 7 microU/ml) especially during daytime (49 +/- 11 microU/ml vs 37 +/- 9 microU/ml, P less than 0.03), suggesting that a decreased insulin degradation was not a major factor in the difference in insulin requirements. The effect of an acute change in azotaemia on insulin requirements was also evaluated in 4 uraemic diabetics on chronic haemodialysis the day prior to and the day after a routine dialysis (serum creatinine 922 +/- 59 mumol/l vs 555 +/- 109 mumol/l). No difference in insulin administration on the two days was observed (42.5 +/- 6.1 U vs 43.2 +/- 5.6 U). It is concluded that insulin resistance is present in uraemic insulin-dependent diabetics analogous to the insulin resistance widely prevalent in non-diabetic uraemic patients. The abnormality is at least partly reversible after several weeks on chronic dialysis, but not acutely. The pathophysiologic mechanisms underlying the insulin resistance in uraemia in the diabetic remain to be clarified.     

Humalog Mix25 offers better mealtime glycemic control in patients with type 1 or type 2 diabetes

To compare the postprandial glucodynamics of Humalog Mix25, (Humalog Mix75/25 in the US; Mix25), to human insulin 30/70 (Humulin 70/30 in the US; 30/70) in patients with type 1 or type 2 diabetes. Ninety-three patients with type 1 diabetes and 84 patients with type 2 diabetes were evaluated in two separate but identical protocols using a randomized, multicenter, double-blind, crossover design. Patients consumed test meals 5 minutes after equal doses of Mix25 or 30/70. Plasma glucose was measured at baseline and 15 minute intervals for 4 hours after the meal. Two-hour postprandial glucose (2pp), 2-hour glucose excursion (2pp(ex) ), glucose versus time area under the curve 0 to 4 hours (AUC(0-4) ) and glucose excursion area under the curve 0 to 2 and 0 to 4 hours (AUCex(0-2), AUCex(0-4) ) were calculated. For the combined patient population, Mix25 resulted in significantly lower 2pp (12.45 +/- 3.59 vs. 13.47 +/- 3.62 mmol/L; p <0.001), AUC(0-4) (44.45 +/- 12.20 vs. 47.25 +/- 11.97 mmol x h/L; p <0.001), and glucose excursion parameters: 2pp(ex) (3.20 +/- 2.72 vs. 4.40 +/- 2.81 mmol/L; p <0.001), AUCex(0-2) (5.45 +/- 3.15 vs 6.60 +/- 3.13 mmol x h/L; p <0.001), and AUCex(0-4) (7.57 +/- 8.37 vs. 11.02 +/- 8.47 mmol x h/L; p <0.001) compared to 30/70. Further analysis of the treatment by type of diabetes indicated that Mix25 provided nearly identical glucose excursion responses in type 1 and type 2 diabetes up to 2 hours after the test meal, in contrast to 30/70. Pre-meal injection of Mix25 resulted in lower postprandial blood glucose levels compared to 30/70. The postprandial blood glucose response following Mix25 was similar in patients with either type 1 or type 2 diabetes.     

Hypoglycemic potential of nateglinide versus glyburide in patients with type 2 diabetes mellitus

Antidiabetic agents that augment insulin secretion can cause hypoglycemia. With the current trend toward early and aggressive treatment of patients with type 2 diabetes, the hypoglycemic potential of insulinotropic agents is of concern. This study aimed to compare the propensity of the "glinide," nateglinide, and the sulfonylurea (SU), glyburide, to elicit hypoglycemia in type 2 diabetic patients with moderately elevated fasting plasma glucose (FPG). Hyperglycemic clamps (target plasma glucose = 11.1 mmol/L) were initiated, and 30 minutes later patients received a single oral dose of nateglinide (120 mg, n = 15) or glyburide (10 mg, n = 12) in a double-blind fashion. At the end of the 2-hour clamp when the glucose infusion was terminated, plasma glucose and insulin levels were measured for 4 additional hours. The minimum plasma glucose level achieved after terminating the glucose infusion (glucose nadir) was used as an index of hypoglycemic potential. The mean (+/-SEM) glucose nadir was significantly lower in patients given glyburide (3.3 +/- 0.2 mmol/L) versus nateglinide (4.4 +/- 0.3 mmol/L, P = .025). Confirmed hypoglycemia (plasma glucose < or = 2.8 mmol/L) occurred in 2 of 12 patients given glyburide and in none of those given nateglinide. Plasma insulin levels were significantly higher from 100 to 240 minutes after clamp termination in patients given glyburide versus nateglinide. Nateglinide has less hypoglycemic potential than glyburide, suggesting that nateglinide may be a more appropriate insulinotropic agent for patients with moderate fasting hyperglycemia, such as elderly patients and those with comorbid cardiac ischemia.