Serum insulin,insulin antibodies and insulin requirement in the first period of insulin treatment in non-insulin resistant diabetics

Summary Twelve insulin-sensitive diabetics were studied for 200 days after the initiation of mixed beef-pork NPH insulin. Normalization of the fasting blood glucose was not accompanied by any elevation in the pre-treatment fasting immunoreactive insulin level. Insulin antibodies appeared in 2 patients on the second week of insulin treatment, in 6 others within 87 days. In 4 patients no antibodies were found 200 days after the start of insulin. The appearance of antibodies was accompanied in two patients by a decrease in insulin requirement, in others there was no change. When antibodies were present, the total maximum insulin binding capacity was 4 to 12 U/1, but the total insulin constituted only 3 to 36% of the binding capacity. Insulin wastage caused by the destruction of the immune complexes was calculated to be 0.35 to 5.6 U/die only, and this explains the negligible effect of insulin antibodies on insulin requirement in non-resistant patients. Presented at the 10th Annual Meeting of the European Association for the Study of Diabetes in Jerusalem, September 11–13, 1974.     

Overnight basal insulin requirements in insulin dependent diabetics

Programming open loop insulin delivery systems makes necessary the knowledge of patients insulin needs. It is frequently postulated that insulin needs increase at the end of the night in relation to the rise in cortisol secretion. According to this hypothesis is it justified to speed up the insulin infusion rate in the early morning? This question was addressed by studying insulin infusion rate by an artificial pancreas during the night in 12 C. peptide negative insulin dependent diabetics. They were connected to the artificial pancreas from 8 a.m. to 10 a.m. the next morning while on their habitual diabetic diet and slept as usual from 11 p.m. to 7 a.m. approximately. From 11 p.m. to 7 a.m. mean insulin infusion rate was 21.5 +/- 3.3 mU/Kg/h representing 15.6 +/- 1.6% of the dose delivered in 24 hours. Blood glucose was stable around 85 mg/dl. No significant differences were observed in the hourly insulin infusion rate during the night period, in spite of a slight tendency to a rise (from 21.1 +/- 2.8 to 22.1 +/- 2.6 mU/kg/h) tendency to a rise (from 21.1 +/- 2.8 to 22.1 +/- 2.6 mU/kg/h) after 4 a.m. On the basis of these results obtained in patients sleeping as usual it does not appear useful to envisage a systematic acceleration of insulin infusion rate by continuous delivery systems in the early morning.     

Characterization of circulating insulin in insulin autoimmune syndrome

We examined the forms of circulating insulin in three patients with the insulin autoimmune syndrome by a method combining gel filtration and reverse phase high performance liquid chromatography (RP-HPLC). Insulin bound to circulating antibody was dissociated by molecular sieve chromatography at acid pH. The free insulin peak eluted from a Sephadex G-50 column was subsequently chromatographed on a Bio-Gel P-30 column. In all three patients, insulin coeluted with normal human insulin. However, when the partially purified insulins, obtained by gel filtration, were applied to RP-HPLC, an abnormally migrating insulin was found in two of three patients. The insulins were more hydrophobic than normal human, porcine, or bovine insulin, but were different from each other. A third patient had only a single insulin peak on RP-HPLC which corresponded to normal insulin. In contrast, the insulin from insulin-treated diabetic patients with antibodies to exogenous insulin corresponded to either porcine or bovine and normal human insulin. The antibodies in the circulation of these patients with the autoimmune syndrome were of the immunoglobulin G type and contained kappa and lambda-chains in the same proportions as antibodies in insulin-treated patients. Autoantibodies could not be distinguished from those secondary to exogenous insulin treatment on the basis of displacement of binding by human, beef, or pork insulin. These results suggest that in certain patients with the insulin autoimmune syndrome, there may be a molecular abnormality of circulating insulin. Whether this comprises a cause for the syndrome or is a result of posttranslational processing of insulin remains to be determined.     

Relationship between insulin resistance, insulin secretion and insulin metabolism in simple obesity

The study was designed to evaluate whether the correlation occurring in simple obesity between insulin resistance and peripheral hyperinsulinemia corresponds to a relationship between insulin resistance and insulin overproduction by the pancreas. In addition, the study investigated the relation existing in simple obesity between insulin resistance and insulin metabolism. For these purposes, we measured and correlated: (1) insulin sensitivity, estimated by glucose disappearance rate from plasma after intravenous insulin injection; (2) insulin secretion by the pancreas, estimated by fasting C-peptide levels in peripheral blood; (3) insulin metabolism, estimated by means of C-peptide: insulin molar ratio in peripheral blood. Twenty-five subjects (20 females, five males) aged 21 to 59 years were studied. All were obese and had a normal glucose tolerance. Glucose disappearance rate from plasma after i.v. insulin injection averaged 3.65 +/- 0.42 mg/dl/min (mean +/- s.e.m.). Fasting C-peptide was 0.90 +/- 0.09 nmol/l. Fasting C-peptide: insulin molar ratio averaged 5.94 +/- 0.48. Negative correlations were found between glucose disappearance rates after i.v. insulin injection, ie, insulin sensitivity, and fasting concentrations of both insulin (r = -0.806, P less than 0.001) and C-peptide (r = -0.525, P less than 0.01). A positive relationship was found between glucose disappearance rate from plasma after i.v. insulin injection and fasting C-peptide: insulin molar ratio, ie, insulin metabolism (r = 0.707, P less than 0.001). We conclude that in simple obesity insulin overproduction by the pancreas is negatively related to insulin resistance, and insulin resistance and impaired insulin metabolism are strictly related phenomena.     

免疫原性与特异性胰岛素检测对胰岛β细胞功能评估的比较

在不同糖耐量者同时检测免疫原性胰岛素(IRI)与特异性胰岛素,发现虽然数值不同,但两种测定方法对于评估不同糖耐量者胰岛β细胞分泌功能及胰岛素敏感性的效果是一致的,提示测定IRI仍有临床实用价值.     

Influence of insulin treatment on insulin sensitivity in insulin requiring type 2 diabetes patients

Insulin resistance in type 2 diabetes subjects was investigated before and 6 months after insulin administration in 43 type 2 diabetes patients (28 females and 15 males). Their age was 56.1+/-8.6 years, diabetes duration 11.7+/-6.8 years, BMI 29.5+/-5.3 kg/m2. All patients were on maximal dosage of oral hypoglycaemic agents and had poor metabolic control (HbA1c 11.2+/-1.6%). Insulin sensitivity was measured by euglycaemic clamp (insulin infusion rate 1 mU kg-1 min-1). The glucose disposal rate (M-value) was considerably lower in patients (2.4+/-1.6 mg kg-1 min-1, 0.2-8.1) compared with healthy subjects (7.1+/-0.2 mg kg-1 min-1, p<0.01). M-value was strongly associated with WHR (r=-0.41, p<0.05). The patients with poorest insulin sensitivity had the highest level of total cholesterol (r=-0.41, p=0.02) and LDL-cholesterol (r=-0.38, p=0.03). After 6 months of insulin treatment BMI was 30.3+/-4.2 kg/m2 (p<0.05), mean weight increase was 2.7+/-0.8 kg. M-value was substantially increased to 4.5+/-2.3 mg kg-1 min-1 (p<0.001), the degree of improvement depended on basal insulin sensitivity (r=-0.55, p<0.01). HbA1c was reduced to 7.7+/-1.4% (p<0.01), the correlation M-value with change of HbA1c (r=-0.59, p<0.01) was shown. Total cholesterol decreased from 6.3+/-1.1 to 5.4+/-1.1 mmol/l, LDL-cholesterol from 4.1+/-1.1 to 3.4+/-1.0 mmol/l, triglycerides from 2.6+/-1.6 to 1.6+/-0.7 mmol/l (p<0.001). In conclusion, insulin treatment of type 2 diabetes patients leads to decrease in insulin resistance due to reduction in glucose toxicity and plasma atherogenicity despite weight gain.     

The renal metabolism of insulin: urinary insulin excretion in patients with mutant insulin syndrome (insulin Wakayama)

Many studies have shown that the kidney plays an important role in the metabolism of many proteins and small peptides. To understand insulin handling in the kidney, we examined urinary insulin excretion under several conditions in patients with mutant insulin syndrome (MIS; insulin Wakayama). Urinary excretion of insulin was studied using high-performance liquid chromatography analysis in patients with MIS. In these patients, most of the insulin extracted from a 24-hour urine collection and from urine collected after stimulation of insulin secretion by glucose or glucagon was normal insulin, whereas 90% of serum insulin is structurally abnormal (Leu-A3 insulin). On the other hand, arginine, which is known as an inhibitor of renal tubular reabsorption, increased urinary excretion of Leu-A3 insulin. The ratio of Leu-A3 and normal insulin in urine after arginine was similar to that in serum. A large amount of Leu-A3 insulin is excreted in urine when reabsorption of insulin at renal tubules is inhibited by arginine. These data indicate that normal and Leu-A3 insulin are filtered through the glomerulus with relatively little restriction. Using the fact that basal urine has a high concentration of normal insulin and an extremely low concentration of Leu-A3 insulin, which has less receptor-binding affinity, we speculated some possibilities. One possibility is that both forms of insulin are reabsorbed by the tubular cells, but with different efficiencies. Leu-A3 insulin absorption in more complete, and this suggests differences in the uptake pathways that may account for the differences in response to arginine infusions. Another possibility is that only normal insulin is secreted from tubules into urine which is mediated by receptors. Our results provide new insight into renal metabolism of insulin and showed that MIS is a useful model for studying it.     

Relationships between insulin secretion, insulin metabolism and insulin resistance in mild glucose intolerance

The aim of this study was to evaluate whether the correlation between insulin resistance and peripheral hyperinsulinaemia existing in mild glucose intolerance corresponds to a relationship between insulin resistance and insulin overproduction by the pancreas. In addition, the possibility that insulin resistance is related to insulin metabolism was examined. Twenty five subjects with fasting normoglycaemia and an abnormal glucose response to the oral glucose tolerance test (OGTT) were studied. Insulin secretion by the pancreas was estimated by means of fasting C-peptide levels in peripheral blood. Insulin resistance was estimated by the rate of glucose disappearance from plasma after i.v. insulin injection. Insulin metabolism was estimated indirectly by the C-peptide: insulin molar ratio. A negative correlation was found between the glucose disappearance rate from plasma after i.v. insulin injection and fasting insulin levels (r = -0.677, p less than 0.001), but not fasting C-peptide concentrations (r = -0.164, p = NS). Glucose disappearance rate from plasma correlated positively with the C-peptide: insulin molar ratio (r = 0.626, p less than 0.001). These results suggest that in mild glucose intolerance insulin resistance and insulin secretion by the pancreas are not related phenomena, and that the defect responsible for insulin resistance might also be implicated in the impaired insulin metabolism.     

Role of insulin in glucose-stimulated insulin secretion in beta cells

Diabetes is on the increase worldwide and greater than 90% are type 2. There are two features to type 2 diabetes: muscle, fat and liver tissues are insulin resistant and beta cells lose the ability to secrete insulin. Prior to developing diabetes, however, insulin resistant individuals lose the first-phase insulin secretion response. Transgenic mice lacking insulin receptors in their beta cells have no first-phase response. Primary cultures of mouse islets pre-exposed to anti-insulin do not exhibit a first-phase insulin secretion response. That is, beta cells, like muscle, fat, and liver, are an insulin sensitive tissue and in the presence of insulin resistance (type 2 diabetes), in the absence of insulin receptors (transgenic mice lacking beta cell insulin receptors), or in the absence of constitutively secreted insulin (anti-insulin treatment), beta cells are unable to respond properly to post-prandial glucose. The purpose of this report is to review our understanding of the glucose-stimulus response and of insulin signaling, and to suggest why the latter may be necessary for the former to proceed.     

Diurnal variations in insulin secretion and insulin sensitivity in aged subjects

Summary Glucose tolerance tends to decrease in healthy aged subjects without family history of diabetes. Either reduced insulin secretion or insulin resistance may be responsible. Insulin secretion and insulin sensitivity were studied in 7 aged subjects (68–75 years) and 8 young controls (21–27 years). A 1-mg i.v. glucagon and a 5-U/m² body area i.v. insulin test were run in each subject at 07⁰⁰ and at 19⁰⁰ on two different days to detect diurnal variations. An arginine test was also performed to evaluate pancreatic glucagon behavior. In the evening, young subjects presented a glucose tolerance impairment with significantly decreased plasma insulin levels, and a reduced hypoglycemic effect of exogenous insulin. Resistance to both endogenous and exogenous insulin in the aged was observed in the morning without significant morning/evening variations. Since the response to contra-insular hormones (GH in the insulin test, glucagon in the arginine test) was the same in both age groups, their role in the phenomenon could be ruled out. It is suggested that in the aged a stable reduction in number and/or a change in affinity of insulin receptors may occur. In addition, since again is seen to be associated with the disappearance of diurnal variations in glucose tolerance and insulin secretion and sensitivity, and since a reduction in the receptor level of young healthy subjects in the evening has been reported by some authors, it is suggested that aged subjects may be less able to modulate the binding of insulin to its peripheral receptors in the course of the day.     

Initiating insulin therapy in type 2 diabetes: benefits of insulin analogs and insulin pens

Despite the development of alternative therapies in recent years, insulin injections remain essential treatment for type 2 diabetes once oral therapy alone becomes inadequate. However, neither patients nor physicians are proactive enough with regard to starting insulin, despite the well-known benefits of early insulin initiation and aggressive dose titration. Barriers to starting insulin therapy are being overcome by developments in insulin and delivery device technology and are the subject of this review. A literature search spanning the last 25 years was carried out to identify publications addressing issues of insulin initiation, how insulin analogs can help overcome barriers to initiation, and the advantages of pen-type insulin delivery systems. Seventy-five publications were identified. These references illustrate that the drawbacks associated with regular exogenous human insulins (soluble and NPH) are improved with modern insulin analogs. The more rapid absorption of prandial insulin analogs compared with human insulin eliminates the need for an injection-meal-interval, increasing convenience, while basal analogs have no discernible peak in activity. Modern insulin delivery devices also have advantages over the traditional vial and syringe. Currently available insulin pens are either durable (insulin cartridge is replaceable; e.g., HumaPen, Eli Lilly [Indianapolis, IN]; NovoPen series, Novo Nordisk [Bagsvaerd, Denmark]) or disposable (prefilled; e.g., FlexPen, Novo Nordisk; SoloSTAR, sanofi-aventis [Paris, France]), with features to aid ease-of-use. These include a large dose selector, dial-up and dial-down facility, and audible clicks when selecting the dose. The potential for dosing errors is thus reduced with pen-type devices, with other benefits including a discreet appearance, ease of learning, and greater user confidence. Collectively, these features contribute to overwhelming patient preference when compared with vials and syringes. Despite the greater cost of insulin pens relative to vials and syringes, improvements in treatment adherence with pens-and hence glycemic control-may offset these costs in the long term.     

The relationship between circulating free and bound insulin, insulin antibodies, insulin dosage and diabetic control in insulin treated diabetics

Free and bound insulin concentrations, blood glucose and anti-insulin antibody binding characteristics have been determined in 100 insulin treated diabetics; medium serum free insulin was 11 mU/l when fasting and rose to 30 mU/l after the mid-day meal. Significant correlation between blood glucose and serum free (but not bound) insulin was found. No relationship between insulin antibodies and daily insulin dose or diabetic control were found, nor a relationship between free insulin and antibody characteristics.     

胰岛素抵抗细胞模型的胰岛素降解酶表达

目的 了解胰岛素降解酶（ＩＤＥ）基因、酶蛋白表达水平与胰岛素敏感性的关系,并初步探讨胰岛素降解抑制剂氯喹改善胰岛素敏感性的分子机制。方法 以的代大鼠肝细胞胰岛抵抗（ＩＲ）模型为研究对象,分别采用免疫印迹技术和逆转录－聚合酶链反应（ＲＴ－ＰＣＲ）技术检测ＩＲ细胞模型的ＩＤＥ酶蛋白表达（ＥＩＰ）及基因表达水平（ＥＩＧ）,同时检测ＩＤＥ活性和反映细胞胰岛素敏感性的＾１４Ｃ－２－脱氧葡萄糖掺入率及＾１４Ｃ     

Free and total insulin integrated concentrations in insulin dependent diabetes

Studies of the 24 hr insulin concentration profiles in diabetic subjects on chronic exogenous insulin have been hampered by the presence of endogenous anti-insulin antibody, which gives spurious estimates of radioimmunoassayable insulin concentrations. The introduction of polyethylene glycol precipitation of endogenous antibody has allowed development of reliable assays for determiniation of free and total insulin concentration in subjects on insulin therapy. This article reports our observations of plasma free and total insulin concentration in 50 Type I and Type II ambulatory insulin dependent diabetics, utilizing a continuous 24 hr blood withdrawal technique. In response to exogenous insulin, study subjects had marked elevations in insulin concentrations compared to controls. Mean free insulin integrated concentration was 3.5-fold higher in diabetics than nondiabetics. Mean total insulin integrated concentration was 868 μU/ml, more than 20 times in excess of total insulin concentration in nondiabetics. There was a wide range among diabetics in the percentage of total insulin in the free insulin fraction. Neither free nor total insulin integrated concentration correlated with dose of exogenous insulin. Free and total insulin concentration profiles showed a limited range of variation in insulin concentration during the 24 hr of study, no subject having a profile that mimicked that observed in nondiabetic subjects. Glucose integrated concentration showed no correlation with free insulin integrated concentration, however, it did correlate inversely with the percentage of total insulin in the free insulin fraction. These data emphasize the difficulty in establishing normal patterns of insulin among diabetic subjects on conventional subcutaneous insulin therapy.