Plasma testosterone in adult normoglycaemic men: impact of hyperinsulinaemia.

Summary This study analysed the relationship of plasma testosterone with β-cell secretion, insulin sensitivity and other pituitary-target gland hormones in normoglycaemic adult men. The sample frame was the ‘Offspring of individuals with diabetes study’ database. A total of 358 offspring of individuals with type-2 diabetes (T2DM) and 287 individuals without known family history of T2DM were recruited for the study. Normoglycaemic men aged ≥18 years (maximum 55) were selected for this analysis. All participants underwent 75 g oral glucose tolerance test (OGTT); blood samples were collected at 0, 30, 60 and 120 min for plasma insulin and C-peptide. Total testosterone, cortisol, adrenocorticotropic hormone, thyroid stimulating hormone and thyroxine (T4) were measured in the fasting sample. A total of 164 men (age 28 ± 7.7 years) were included in analysis. Testosterone correlated negatively with BMI, waist to hip ratio (WHR), area under curve (AUC) of C-peptide and insulin (during OGTT) and was positively correlated with insulin sensitivity (r ~ 0.4). Cortisol and T4 positively correlated (weak) with testosterone (r ~ 0.2). In multivariate analysis, AUC C-peptide, BMI, WHR (negatively) and cortisol (positively) were related to testosterone. Concluding, testosterone correlated negatively with BMI and β-cell secretion. There was a positive association of testosterone with insulin sensitivity, cortisol and T4.