Relationship between insulin sensitivity and circulating sex hormone-binding globulin levels in hyperandrogenic obese women.

The aim of this work was to examine the effect of an insulin infusion on SHBG levels as well as the relationship between SHBG levels and insulin sensitivity. Acute insulin infusion was used with the insulin-glucose clamp technique. The subjects were 14 consecutive well-characterized hyperandrogenic non-diabetic obese women without biological and echographic symptoms of polycystic ovary syndrome. Adiposity and fat distribution were assessed respectively by the body mass index (BMI: 38.7 +/- 1.6 kg/m2) and by the waist hip ratio (WHR: 0.91 +/- 0.01). Hyperandrogenism was evidenced by hirsutism and serum testosterone greater than 2.8 nM. Circulating SHBG levels were determined in the fasting state by RIA. Insulin sensitivity was assessed using the euglycemic hyperinsulinemic glucose clamp technique with three incremental doses of insulin. Seven non-obese non-hyperandrogenic subjects (BMI: 21.0 +/- 0.6 kg/m2) served as controls for the study of the insulin resistance state. Because of supraphysiological insulin infusion rates (40, 100, and 350 mU/min.m2, each dose for 2 h), insulin sensitivity was mainly studied at peripheral level. We calculated the Km, i.e. the ED50 of the dose-response curve, the glucose disposal rate, and the maximal glucose disposal rate per U insulin (M/I). The hyperandrogenic obese subjects exhibited marked insulin resistance. SHBG levels, although already in the lower half of normal in the basal state, decreased from 34.8 +/- 3.4 nmol/l to 29.7 +/- 3.3 nmol/l (P = 0.001; normal values are 18-83 nmol/l).(ABSTRACT TRUNCATED AT 250 WORDS)

Metformin effects on peripheral sensitivity to insulin in non diabetic obese subjects.

Using the euglycaemic insulin-clamp technique we examined the effects of one-month metformin treatment on peripheral glucose utilization in non diabetic obese subjects. Two groups of obese subjects were studied in comparison with untreated lean women. Group 1 (n = 6) experienced weight loss (BMI: 32.6 +/- 1.7 vs 34.8 +/- 1.6 kg/m2, p < 0.05) but not group 2 (n = 7; BMI before and after treatment: 34.6 +/- 3.2 and 34.8 +/- 3.1 kg/m2). After a continuous insulin infusion of 40, 100, and 350 mU/m2/min we estimated the tissue sensitivity to insulin by the determination of Km, the glucose disposal (M), and the amount of glucose metabolized per U insulin (M/I ratio). After the metformin treatment the mean Km decreased by 31% in group 1 (p < 0.05) but not significantly in group 2; M and M/I were not modified in the two study groups. In conclusion, in non diabetic obese subjects, metformin seems not to affect peripheral insulin-mediated glucose metabolism unless there is weight loss.

[Female obesity: testosteronemia is positively correlated with peripheral insulin resistance]. / Obésité féminine: la testostéronémie est postivement corrélée à l'insulinorésistance périphérique.

Hyperinsulinemia and hyperandrogenemia are frequent in obese women. The aim of this study is to examine the relationship between the degree of insulin resistance and plasma androgens, and the role of android obesity. We studied 16 obese (BMI = 39.3 +/- 1.6 kg/m2) premenopausal non diabetic women (age = 28.2 +/- 1.4 years). The peripheral insulin sensitivity was determined during an euglycemic insulin clamp study. Serum total testosterone (TT), free testosterone (FT), androstenedione (A) were measured in each women. We compared these results to those of 5 control subjects (BMI = 20 +/- 1 kg/m2). Insulin resistance was more severe in the obese women than in the control subjects: Vmax = 9.1 +/- 0.5 mg/kg/mm vs 19.1 +/- 1.0 mg/kg/mn (p < 0.01) and Km = 152.2 +/- 13.9 microU/ml vs 42.6 +/- 5.8 microU/ml (p < 0.01). Significant positive correlations were demonstrated in the obese women between Km and both total testosterone (r = 0.74; p < 0.01) and free testosterone (r = 0.52; p < 0.05). There was no correlation between Km and Androstenedione. The waist to hip ratio (WHR) differentiated two groups of age--and weight-matched obese women; Gr 1:10 upper body obese women (WHR = 0.90 +/- 0.10; BMI = 39.0 +/- 1.9 kg/m2); Gr 2: 6 lower body obese (WHR = 0.77 +/- 0.02; BMI = 40.0 +/- 3.1 kg/m2. Insulin resistance was more severe in the Gr I: Km = 174 +/- 17 microU/ml, than in the Gr 2: Km = 101 +/- 8 microU/ml (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Thyroid hormone extraction by plasma exchange: a study of extraction rate.

How to obtain an optimal efficiency of plasma exchanges in the treatment of severe hyperthyroidism has not been defined. In order to evaluate how long the exchanges must be continued to be fully effective in extracting thyroid hormones, we evaluated the extraction rate by repeated plasma sampling in two hyperthyroid patients and three euthyroid subjects who underwent a total of seven exchanges. Plasma concentrations of thyroid hormones were also determined just before, just after, and 24 hours following the exchange. The hormonal removal rate did not fall dramatically during the exchange, so that its efficiency--in terms of hormone extraction--depends closely on its duration. The determination of plasma thyroid hormone concentrations after the exchange does not appear to be useful in evaluating the thyroid hormone loss since these concentrations may not change in spite of the hormonal extraction.