Testosterone and diurnal rhythmicity of leptin, TNF-alpha and TNF-II receptor in insulin-resistant myotonic dystrophy patients

OBJECTIVE: To investigate the leptin and TNF systems in relation to testosterone in insulin resistant myotonic dystrophy (DM1) subjects. DESIGN AND SUBJECTS: Fasting morning samples and diurnal sampling during 24 h. Forty-two DM1 subjects (20 women and 22 men; age 41.5 (28.5-58.7)y, body mass index (BMI) 23.3 (18.6-29.2)kg/m(2); median and 10th and 90th percentile, respectively). Fifty healthy volunteers (23 women and 27 men; age 42 (27.0-56.9)y, BMI 24.0 (20.7-29.7) kg/m(2)). Nine men with DM1 and nine healthy men participated in diurnal sampling. MEASUREMENTS: Body composition was measured by bioelectric impedance analysis. Circulating levels of leptin, TNF-alpha, TNFR-II, insulin, testosterone and lipids were measured. The number of CTG triplet repeats was analysed. RESULTS: Basal as well as median 24 h levels of leptin and TNFR-II were significantly increased in DM1 patients, independent of body fat mass. This was associated with higher insulin and lower testosterone levels in DM1 patients. The genetic defect was related to leptin and TNFR-II levels in DM1 patients. CONCLUSION: Hyperleptinemia in DM1 is clearly linked to the concomitant hypogonadism. The genetic defect may directly or indirectly contribute to increased leptin levels. Increased exposure of cytokines may contribute to insulin resistance and other hormonal disturbances in DM1.