Brand JS et al. – In middle–aged and older men, low endogenous testosterone and SHBG levels are associated with glycaemia, even below the threshold for diabetes.

• Cross–sectional study of 1292 men from the Norfolk population of European Prospective Investigation into Cancer (EPIC–Norfolk).
• Glycated haemoglobin, total testosterone (TT) and SHBG levels were measured, and free testosterone (FT) levels were calculated.
• Multiple linear regression models were used to assess the associations of TT, SHBG and FT with HbA1c.

• Men with diabetes had lower testosterone and SHBG levels.
• In non–diabetic men, HbA1c levels were inversely associated with TT and calculated FT independently of age, body mass index, smoking, alcohol consumption and physical activity.
• The adjusted change in HbA1c was 0.055 (95% CI 0.025; 0.085) per standard deviation (SD) decrease in TT and 0.041 (95% CI 0.010; 0.073) per SD decrease in calculated FT, respectively.
• SHBG levels were inversely associated with HbA1c after multivariable adjustment (β=0.038 per SD decrease (95% CI 0.004; 0.071)).