<p><b>Objective</b>To compare the level of testosterone between type-2 diabetes mellitus (T2DM) patients and healthy controls and to investigate the status of hypogonadism and the influence of hypopgonadism on the quality of life.</p><p><b>METHODS</b>We collected serum total testosterone (TT), free testosterone (FT), sex hormone-binding globulin (SHBG), and other clinical data from 166 T2DM patients aged over 30 years and 186 age-matched healthy controls. We investigated the quality of life (QoL) of the two groups of subjects using the questionnaires of Androgen Deficiency in Aging Males (ADAM), Aging Male Symptoms (AMS), 36-Item Short-Form Health Survey (SF-36), and Special Quality of Life for Diabetes Mellitus (DSQL).</p><p><b>RESULTS</b>The level of calculated FT (cFT) was remarkably lower in the T2DM patients than in the healthy controls (P<0.05), but no statistically significant differences were observed between the two groups in the levels of TT, bio-available testosterone (Bio-T), and SHBG. The T2DM males with hypogonadism showed significant differences from those without in age, height, systolic blood pressure, and creatinine (P<0.05). Based on the criteria of cFT <0.3 nmol/L and AMS score ≥27, the incidence rate of hypogonadism was 51.81% in the T2DM patients, 31.58% in the 30－39 yr group, 32.50% in the 40－49 yr group, 50% in the 50－59 yr group, 69.23% in the 60－69 yr group, and 77.27% in the ≥70 yr group, elevated by 77.4% with the increase of 10 years of age (OR = 1.774, P<0.001). The AMS score was significantly correlated with the scores of DSQL (r = 0.557, P<0.001) and SF-36 (r = －0.739, P<0.001) in the T2DM patients.</p><p><b>CONCLUSIONS</b>T2DM patients have lower levels of cFT than healthy men, accompanied with a higher incidence of hypogonadism. Age is a main risk factor of hypogonadism. Severer testosterone deficiency symptoms are associated with lower scores of QoL in T2DM males.</p>