A 3-month randomized placebocontrolled trial I n men, an association between lower plasma total testosterone (PTT) and insulin resistance has been found in cross-sectional studies (1,2) and in one nested case-control study (3) without any possible conclusion in terms of causality or direction of the relationship. Indeed, to obtain such information, randomized controlled trials are needed. Until now, only one clinical trial has suggested that testosterone therapy improves insulin sensitivity in obese men (4). Crosssectional studies concerning leptin regulation by androgens have provided no definitive conclusions as to whether the negative association between androgens and leptin level is independent (5) or dependent (6). This randomized controlled trial was designed to assess the role of androgens on insulin sensitivity and leptin regulation in healthy adult men.This study was a randomized, double-blind, unicentric, controlled, clinical trial. Three treatments (testosterone, dihydrotestosterone [DHT], and placebo) were compared in parallel groups during a 3-month period. All of the examinations were performed by only two physicians, using a standardized protocol. Blood was drawn between 8:00 A.M. and 9:30 A.M. after an overnight fast to determine fasting plasma glucose, insulin, leptin, sex hormones, lipids, coagulation and fibrinolysis parameters, hepatic enzymes, and prostate-specific antigen (PSA) and blood cell count. Then, a standard 75-g oral glucose tolerance test and a digital rectal examination were performed. In addition, between days 10 and 20, all of the subjects were monitored to measure sex hormones in order to adapt the treatment dose. The study protocol was approved by the Henri Mondor Hospital Ethics Committee. All of the included subjects gave written informed consent.Men with low levels of PTT (confirmed by two measurements) were selected from a large occupation-based population. The inclusion criteria were as follows: 1) either PTT Յ3.4 ng/ml [5th percentile value of PTT distribution in the 1,718 men of the TELECOM Study (7)] from 1985 to 1987 and Ͻ4.0 ng/ml (13th percentile value) from 1992 to 1993 (3) or PTT Ͻ4.0 ng/ml from 1992 to 1993 and Ͻ4.0 ng/ml a few days before inclusion; 2) no history of vascular thrombosis or ischemic heart disease; 3) no treatment by androgens, anti-androgens, and antidiabetic or antithrombotic drugs; 4) normal values of plasma prolactin, estradiol, and thyroxin; 5) no current prostatic disease and a normal PSA value. A total of 18 healthy men with stable low plasma androgens (Table 1) and a range of PTT from 1.4 to 3.7 ng/ml at baseline were included.The 18 selected men were randomly assigned to one of three treatment groups: testosterone, DHT, or placebo. The randomization code was known only to the study manager. Treatment was a gel administered every morning by percutaneous route. The daily dose during the first weeks was 125 mg for the testosterone and 35 mg for the DHT treatment groups. The adaptation of treatment doses between days 10 and 20 aimed at obtain...

Plasma insulin is a risk factor for diabetes mellitus and cardiovascular disease in men. We investigated the association between plasma testosterone and plasma insulin in an occupational sample of 1292 healthy adult men. Total plasma testosterone decreased with each decade of age and insulin increased with each decade of age. In these cross-sectional data, this significant graded inverse association between testosterone and insulin was independent of age. The association was reduced but not explained by the addition of obesity and subscapular skinfold to the model. Adjustment for alcohol consumption, cigarette smoking and plasma glucose did not materially alter the association. These results are the reverse of the positive association of androgens with insulin in women and suggest alternative possible explanations for the effect of hyperinsulinaemia on cardiovascular disease risk. Prospective studies will be necessary to determine the direction and causal nature of this association.

From April 1985 to July 1987, 1,408 healthy white men aged 20-60 years in Paris, France, recruited on an occupational basis, underwent a physical examination and measurements of plasma sex hormones in a cross-sectional study. Both total testosterone and estradiol showed a significant stepwise decrease with age (p less than 0.001) starting in the early adult years, while estrone did not vary. These relations of testosterone and estradiol with age remained significant after adjustment for body mass index, subscapular skinfold, and tobacco and alcohol consumptions, and they were not modified by exclusion of the men who reported chronic disease. Both the mechanism for the early decrease in testosterone and its clinical significance merit further investigation.

In order to study the relationship between plasma sex-hormone-binding globulin (SHBG) and insulin levels in healthy women, we investigated the association between plasma SHBG and insulin in an occupational sample of 786 nonhormone-using women. Levels of plasma SHBG showed a stepwise decrease with increasing fasting plasma insulin in premenopausal as well as in postmenopausal women. In these cross-sectional data, this significant negative relationship between SHBG and insulin was shown to be independent of age, body mass index, subscapular skinfold, fasting and 2-h plasma glucose in both groups. The etiology and the consequences of this inverse association between SHBG and insulin are unclear. Prospective and clinical studies in women will be necessary to determine the direction and causal nature of the association between SHBG and insulin, as well as its mechanism and its physiological and/or pathophysiological consequences.

Clinical observations and experimental data suggest that sex hormones influence the development of systemic lupus erythematosus (SLE). An imbalance between androgen and estrogen plasma levels may suggest an abnormality in the aromatase activity involved in estradiol synthesis. Aromatase activity in skin and subcutaneous tissue and plasma sex-hormone levels (testosterone, androstenedione, estrone, estradiol, dehydrosterone sulfate, cortisol) were measured in 15 SLE patients (nine female, six male) who had never received corticosteroid treatment and in eight (four female, four male) healthy control subjects. There was a tendency toward an increase in aromatase activity in SLE patients when compared to control subjects. Among SLE patients the aromatase activity varied inversely with disease activity. Patients with SLE had decreased androgen and increased estrogen levels. Aromatase activity in SLE patients had significant direct correlation with estrogen levels. These data suggest that abnormal regulation of aromatase activity may partially explain the abnormalities of estrogen synthesis in SLE.