The aim of the present study was to evaluate the effect of low dose GnRH analogue (Buserelin) on gonadal steroid secretion and hair growth in hirsute women. The drug was administered as a nasal spray (200 micrograms tid) to reduce gonadal steroid secretion. Eight hirsute women were treated for six month with the gonadotropin-releasing hormone analog. All had subclinical polycystic ovary syndromes on the basis of ultrasound or hormonal data, together with ovary dysfunctions and irregular menses. None had adrenal or pituitary dysfunction. The score of hirsutism was evaluated according to Ferriman and Gallway; pituitary function was evaluated measuring the FSH and LH response to GnRH stimulation and gonadal steroid secretion by measuring estradiol, progesterone, total plasma testosterone, androstenedione and androstanediol. Sex hormone binding globulin, insulin, prolactin and DHEA-S were also measured. The suppression of ovarian steroid secretion was confirmed by reductions in total plasma testosterone, and rostenedione and androstanediol that were detectable after one month of treatment. FSH and LH responses to GnRH stimulation were inhibited consistent with pituitary desensitization. No significant side effects were observed and all patients completed the trial. The score of hirsutism was 24 +/- 5 before, 19.6 +/- 6 by the 3rd month and 16.8 +/- 5.1 by the 6th month of treatment (p < 0.001); the effect was still evident 1 and 6 months after the withdrawal of the therapy (14.8 +/- and 15.8 +/- 5 respectively; p < 0.001). Our findings indicate that Buserelin is useful in the treatment of non adrenal hirsutism when other forms of therapy are contraindicated or poorly tolerated by the patient.

To the Editor: Endothelial nitric oxide synthase (eNOS) deficiency was found to affect insulin sensitivity and vascular homeostasis in animal models.1,2 Blood flow regulation by endothelial NO was suggested to modulate glucose uptake in the skeletal muscle.3 Therefore, it is possible that also in human subjects defects in eNOS activation or levels could affect insulin sensitivity.3 The D298D eNOS variant reduces eNOS protein half-life under stress conditions4 and it has been associated to increased cardiovascular disease (CVD) risk.5 The aim of present study was to assess whether among healthy offspring of patients with type 2 diabetes mellitus (T2DM) carriers of the D298D genotype are characterized by insulin resistance and early signs of atherosclerosis. We recruited 142 young white offspring of T2DM with these inclusion criteria: age <45 years, 1 parent affected by T2DM, normal glucose tolerance (fasting plasma glucose <110 mg/dL; …

OBJECTIVE We studied the relationships between plasma IGF-I concentrations and insulin sensitivity in subjects with various degrees of glucose tolerance. RESEARCH DESIGN AND METHODS A total of 357 nondiabetic subjects, 54 subjects with impaired glucose tolerance and 98 newly diagnosed type 2 diabetic subjects, were consecutively recruited, and anthropometric and biochemical characteristics were collected. RESULTS IGF-I concentrations were negatively correlated with age, BMI, waist-to-hip ratio, triglyceride levels, and systolic and diastolic blood pressure. IGF-I concentrations were positively correlated with HDL cholesterol and homeostasis model assessment of insulin sensitivity (HOMA-S). The correlations remained significant after adjusting for sex, age, and BMI. Correlations for HOMA-S with these metabolic and anthropometric variables were of a similar degree and direction to those for IGF-I concentrations. Stepwise linear regression analysis in a model, which included well-known modulators of insulin sensitivity such as sex, age, BMI, glucose tolerance status, family history of diabetes, waist-to-hip ratio, systolic and diastolic blood pressure, HDL cholesterol, and triglyceride levels, revealed that IGF-I concentrations were independently associated with insulin sensitivity accounting for 10.8% of its variation (P < 0.0001). IGF-I concentrations were significantly lower in subjects with World Health Organization (WHO)-defined metabolic syndrome compared with subjects without metabolic syndrome (P < 0.0001). Logistic regression analysis showed that each unit increase in log-transformed IGF-I concentrations was associated with a 90.5% reduction in the risk of WHO-defined metabolic syndrome. CONCLUSIONS These data indicate that IGF-I has the characteristics to be a marker for the insulin resistance syndrome. This suggests that low IGF-I levels may be a useful marker for identifying subjects at risk for cardiovascular disease.

OBJECTIVE The C-174G promoter polymorphism of the interleukin (IL)-6 gene was found to influence transcriptional activity and plasma IL-6 levels in humans. We addressed the question of whether the C-174G IL-6 polymorphism contributes to variation of insulin sensitivity. RESEARCH DESIGN AND METHODS Two cohorts of subjects were genotyped. Cohort 1 includes 275 nondiabetic subjects who underwent a euglycemic-hyperinsulinemic clamp. Cohort 2 includes 77 patients with morbid obesity who underwent laparoscopic adjustable gastric banding (LAGB). RESULTS The genotypes were consistent with Hardy-Weinberg equilibrium proportions. In cohort 1, insulin sensitivity was reduced in carriers of the -174G/G genotype as compared with subjects carrying the C allele (P = 0.004). Carriers of -174G/G displayed significantly higher plasma IL-6 levels in comparison with carriers of the C allele. In a stepwise linear regression analysis, the C-174G polymorphism was independently associated with insulin sensitivity; however, after inclusion of plasma IL-6 concentrations, the polymorphism was excluded from the model explaining insulin sensitivity variability, thus suggesting that the polymorphism was affecting insulin sensitivity by regulating IL-6 plasma levels. IL-6 mRNA levels were measured by real-time RT-PCR in subcutaneous fat obtained from obese patients of cohort 2 during LAGB. Carriers of -174G/G showed increased IL-6 expression compared with subjects carrying the C allele (P = 0.04). There was a significant correlation between adipose IL-6 mRNA expression and insulin resistance assessed by homeostasis model assessment (rho = 0.28, P = 0.014). CONCLUSIONS These results indicate that the -174G/G genotype of the IL-6 gene may contribute to variations in insulin sensitivity.

Ghrelin is a peptide hormone with orexigenic properties that is produced by the stomach. Ghrelin and leptin are thought to be the main regulators of appetite and body weight. The present study was aimed at evaluating the effect of weight reduction after laparoscopic adjustable gastric banding (LAGB) on metabolic parameters and energy balance regulatory peptides. Patients were evaluated before and 6, 12, 24 or 36 months after the procedure, and a blood sample was obtained. Ghrelin rose 6 and 12 months after LABG, and then returned to near-baseline levels. In our study, the correlation between ghrelin and BMI was weak, but a strong significant correlation was maintained between leptin and BMI. We conclude that ghrelin is mainly stimulated by the negative caloric balance, and hypothesize that ghrelin is involved in maintaining a stable body weight, while leptin signals the body energy store; both hormones together are part of a more complex feedback mechanism.

OBJECTIVE The aim of this study was to investigate whether diabetic patients carrying the Arg(972) insulin receptor substrate-1 (IRS-1) variant are at increased risk for secondary failure to sulfonylurea. RESEARCH DESIGN AND METHODS A total of 477 unrelated Caucasian type 2 diabetic patients were recruited according to the following criteria: onset of diabetes after age 35 years, absence of ketonuria at diagnosis, and anti-GAD(-) antibody. Type 2 diabetes was diagnosed according to the American Diabetes Association criteria. Patients with secondary sulfonylurea failure were defined as those requiring insulin due to uncontrolled hyperglycemia (fasting plasma glucose >300 mg/dl) despite sulfonylurea-metformin combined therapy, appropriate diet, and absence of any conditions causing hyperglycemia. RESULTS Of the total patients, 53 (11.1%) were heterozygous for the Arg(972) IRS-1 variant, 1 (0.2%) was homozygous, and the remainder (88.7%) were homozygous for the wild-type allele. The genotype frequency of the Arg(972) IRS-1 variant was 8.7% among diabetic patients well controlled with oral therapy and 16.7% among patients with secondary failure to sulfonylurea (odds ratio 2.1 [95% CI 1.18-3.70], P = 0.01). Adjustment for age, sex, BMI, metabolic control, age at diagnosis, duration of diabetes, and Pro12Ala polymorphism of peroxisome proliferator-activated receptor-gamma2 gene in a logistic regression analysis with secondary failure to sulfonylurea as a dependent variable did not change this association (2.0 [1.38-3.86], P = 0.038). CONCLUSIONS These data demonstrate that the Arg(972) IRS-1 variant is associated with increased risk for secondary failure to sulfonylurea, thus representing a potential example of pharmacogenetics in type 2 diabetes.

Uncoupling protein (UCP)-2 is a member of the mitochondrial inner membrane carriers that uncouple pro-ton entry in the mitochondrial matrix from ATP synthesis. The -866G/A polymorphism in the UCP2 gene, which enhances its transcriptional activity, was associated with enhanced risk for type 2 diabetes in obese subjects. We addressed the question of whether the -866G/A polymorphism contributes to variation in insulin sensitivity by genotyping 181 nondiabetic offspring of type 2 diabetic patients. Insulin sensitivity, assessed by the hyperinsulinemic-euglycemic clamp, was reduced in -866A/A carriers compared with -866A/G or -866G/G carriers (P = 0.01). To directly investigate the correlation between UCP2 expression and insulin resistance, UCP2 mRNA levels were measured by real-time RT-PCR in subcutaneous fat obtained from 100 obese subjects who underwent laparoscopic adjustable gastric banding. UCP2 mRNA expression was significantly correlated with insulin resistance as assessed by the homeostasis model assessment index (r = 0.27, P = 0.007). We examined the association of the -866A/A genotype in a case-control study including 483 type 2 diabetic subjects and 565 control subjects. The -866A/A genotype was associated with diabetes in women (odds ratio 1.84, 95% CI 1.03-3.28; P = 0.037), but not in men. These results indicate that the -866A/A genotype of the UCP2 gene may contribute to diabetes susceptibility by affecting insulin sensitivity.

The insulin receptor substrate-1 (IRS-1) gene has been considered a candidate for insulin resistance, type 2 diabetes, and coronary artery disease. To investigate the relationship between the common Gly972Arg IRS-1 variant and the presence of cardiovascular risk factors, 153 glucose-tolerant, unrelated offspring of type 2 diabetic patients were studied. There were no differences between Arg972 IRS-1 carriers and noncarriers in age, gender, body mass index, waist/hip ratio, body composition, fasting glucose and insulin levels, and glucose or insulin levels during the oral glucose tolerance test. Insulin sensitivity, assessed by hyperinsulinemic-euglycemic clamp, was significantly reduced in carriers of Arg972 IRS-1 (P < 0.03). Carriers of Arg972 IRS-1 displayed many features of the insulin resistance syndrome, including higher values for serum triglycerides (P < 0.01), total/high density lipoprotein cholesterol ratio (P < 0.01), free fatty acid levels (P < 0.04), systolic blood pressure (P < 0.04), microalbuminuria (P < 0.003), and intima-media thickness (P < 0.02). These results suggest that the Arg972 IRS-1 variant could contribute to the risk for atherosclerotic cardiovascular diseases associated with type 2 diabetes by producing a cluster of insulin resistance-related metabolic abnormalities.

We investigated the significance of Gly1057Asp and Leu647Val insulin receptor substrate (IRS)-2 polymorphisms in two Italian cohorts comprising 186 glucose-tolerant subjects and 240 subjects with type 2 diabetes from the Lazio region (i.e. representative of central Italy), and 123 glucose-tolerant subjects from the Sicily region (i.e. representative of south Italy). The allelic frequency of Gly1057Asp variant did not differ between diabetics (32.9%) and nondiabetic subjects, whatever their ethnicity was (35.8% and 33.7% from Lazio and Sicily, respectively). As compared with Gly/Gly subjects within each group, Asp/Asp individuals showed no differences in quantitative traits, including fasting insulin and C-peptide, and several indices of insulin sensitivity and secretion. Only one of the diabetic patients was heterozygous for the Leu647Val variant, and none of the control subjects carried this variant. This patient had three children who were also heterozygous for this variant. They were glucose tolerant, and their insulin sensitivity and insulin secretion indices were within the range of age-matched controls. We also analyzed IRS-2 function in fibroblasts from carriers of Gly1057Asp or Leu647Val variant. No defects in IRS-2 expression, insulin-stimulated phosphorylation, or binding to the p85 subunit of phosphatidylinositol 3-kinase were observed. These results strongly argue against a major role of IRS-2 polymorphisms in the pathogenesis of type 2 diabetes.

It was reported that the common -866G/A polymorphism in the promoter of the human uncoupling protein-2 (UCP2) gene, which enhances its trascriptional activity, is associated with increased mRNA levels in human adipocytes and reduced risk of obesity. Studies in knockout mice and beta-cells indicate that UCP2 may play a role in beta-cell function. In this study, we addressed the question of whether the common -866G/A polymorphism in UCP2 gene contributes to the variation of insulin secretion in humans by genotyping 301 nondiabetic subjects who underwent an oral glucose tolerance test. Glucose-stimulated insulin secretion estimated by several indexes of beta-cell function was significantly lower in carriers of the -866A/A genotype compared with -866A/G or -866G/G according to the dosage of the A allele (P = 0.002-0.05). To investigate directly whether the UCP2 -866G/A polymorphism affects human islet function, pancreatic islets isolated from two -866G/G homozygous, seven -866G/A heterozygous, and one -866A/A homozygous nondiabetic donors were studied. Islets from -866A/A homozygous had lower insulin secretion in response to glucose stimulation as compared with -866G/G and -866G/A carriers. These results indicate that the common -866G/A polymorphism in the UCP2 gene may contribute to the biological variation of insulin secretion in humans.

Objective: The present study aimed at evaluating the acute effect of increasing doses of octreotide (OCT), a long-acting somatostatin analogue, on glucose tolerance and insulin secretion. Methods: A standard and two other oral glucose tolerance tests 30 min after subcutaneous administration of OCT were performed in randomized order in each subject. Obese subjects received 10, 25, or 50 µg of OCT; control subjects received only 10 and 25 µg. Fifteen obese and 10 control subjects were studied; all of them had a normal glucose tolerance. Plasma glucose and insulin levels were measured at times –30, 0, 30, 60, 90, 120, 150, and 180 min after the glucose tolerance test. Results: The results demonstrated that, following OCT administration, both control and obese subjects developed a reduced glucose tolerance, a delayed glycemic peak, and an increase of late plasma glucose values. Fasting as well as stimulated insulin secretions were higher in obese subjects as compared with controls, and insulin secretion was inhibited in a dose-dependent manner by OCT. Conclusions: These data indicate that the action of OCT might be due to at least two different cooperative mechanisms: (1) a delayed glucose absorption, as suggested by the delay of glycemic peak, and (2) a direct or vagal-mediated effect on β-cells, as suggested by the reduction of the area under the curve values in spite of the elevated late glycemic levels. It is noteworthy that doses of OCT as low as 10 and 25 µg are sufficient to inhibit insulin secretion both in normal and obese subjects.

Insulin/IGF-I hybrid receptors composed of an insulin receptor (IR) alphabeta-hemireceptor and a type 1 IGF receptor (IGF-IR) alphabeta-hemireceptor are formed in tissues expressing both molecules. To date there is a limited information about the proportion of hybrids in tissues of normal or diabetic subjects. In this study, we determined the abundance of hybrids in fat from control and NIDDM subjects by using a microwell-based immunoassay. Microwells coated with MA-20 anti-IR or alpha-IGF-IR-PA anti-IGF-IR antibody were incubated with tissue extracts. Immunoadsorbed receptors were incubated with 125I-insulin or 125I-IGF-I in the presence or absence of unlabeled ligands, and hybrids were quantitated as the fraction of 125I-IGF-I binding immunoadsorbed with MA-20. Abundance of hybrids was increased in NIDDM patients as compared with controls (B/T = 1.29 +/- 0.18 and 0.52 +/- 0.06%; P < 0.008, respectively), and it was inversely correlated with both IR number (r = -0.65; P < 0.002), and in vivo insulin sensitivity measured by insulin tolerance test (r = -0.75; P < 0.005), whereas it was positively correlated with insulinemia (r = 0.63; P < 0.003). Insulin binding affinity was lower in NIDDM subjects than in controls (ED50 = 1.87 +/- 0.32 and 0.54 +/- 0.20 nmol/l; P < 0.009, respectively), and was correlated with the percentage of hybrids. Maximal IGF-I binding was significantly greater in NIDDM patients than controls and was positively correlated with the percentage of hybrids whereas IGF-I binding affinity did not differ between the two groups. Results show that expression of hybrids is increased in fat of NIDDM patients compared to control subjects and is correlated with in vivo insulin sensitivity thus raising the possibility that alterations in expression of hybrids which bind IGF-I with higher affinity than insulin may contribute, at least in part, to insulin resistance.

Androgen receptors have been found in human larynx and androgens have been supposed to play an important role in promoting the growth of laryngeal carcinomas. The molecular mechanism underlaying this phenomenon is not at all understood. Aim of this work was to investigate the effects of two androgens (testosterone and dihydrotestosterone) on insulin receptor mRNA levels and insulin binding activity as well as on either metabolic or growth-promoting actions of insulin in a human larynx carcinoma cell line (HEp-2). We found that HEp-2 cells express a high affinity insulin receptor. Both androgens significantly increase insulin receptor mRNA levels and insulin receptor number in HEp-2 cells. Insulin action, evaluated either as total glucose utilization or as [3H]thymidine incorporation into DNA, significantly increased in HEp-2 treated with androgens in comparison to control cultures. Altogether, our data allow us to speculate that the increased insulin effectiveness we observed in the larynx carcinoma cell line HEp-2 after androgen treatment might be involved in the regulation of larynx cancer cells growth.

The IgG from a patient (Italy 2 [I-2]) with hypoglycemia, due to autoantibodies to the insulin receptor, was purified on protein A Sepharose into two fractions that were tested in various human tissues and cells. The IgG fraction that bound protein A (absorbed IgG [IgGa]) nearly completely inhibited the binding of 125I-labeled insulin to various cells or tissues (placenta, IM-9, adipocytes, HEp-2-larynx cells, Epstein-Barr virus lymphocytes) but not >50% of 125I-labeled insulin binding to human liver membranes. Conversely, both the IgG fraction from this patient, which did not bind protein A (flow-through IgG [IgGb]), and the IgGa fraction from a second similar patient (Italy 1 [I-1]) almost completely inhibited the binding of 125I-labeled insulin to liver membranes. The IgGa fraction from patient I-2 did not change receptor affinity because 50% inhibition of 125I-labeled insulin binding was not affected by either the presence or absence of these IgG fractions. Furthermore, liver binding data were not due to cross-reaction of 125I-labeled insulin to the insulinlike growth factor I receptor, and treatment of liver membranes with neuraminidase did not alter the inhibitory effect of the IgGa fraction from patient I-2 on 125I-labeled insulin binding to liver. Binding inhibition experiments performed with cells transfected with and overexpressing the −12 (human insulin receptor [HIR]-A) or the +12 (HIR-B) variant of HIR revealed that the IgGa fraction from patient I-2 inhibited 125I-labeled insulin binding to the HIR-A receptor but not to the HIR-B receptor. The data reported herein demonstrate that the two naturally occurring insulin-receptor variants are immunologically distinct and indicate that the HIR-B variant is predominantly expressed in liver compared with other human tissues.