Relationship Between Testosterone Levels And Type 2 Diabetes In Men

Object: To evaluate the serum testosterone levels of type 2 diabetes in men and to explore the relationship between serum testosterone levels, obesity, insulin resistance, glucose and lipid metabolism.Methods: This study was carried out on 120 men who were diagnosed as type 2 diabetes. Patients with known history of severe hepatic disease, renal failure, infection, or other endocrine diseases were excluded from the study. Fasting blood samples were obtained to measure serum total testosterone, LH, FSH (sex hormones were measured by electrochemiluminescence), glucose, insulin, C peptide, HbA1c, total cholesterol, total triglyeride, HDL-C, LDL-C, apoA-I, apoB and apoE. The duration of diabetes and clinical data were collected systematically. Height and weight were measured by standard procedures by calculating body mass index (BMI) as weight (kilograms) divided by the square of the height (meters), the waist to hip ratio (WHR) was calculated as waistline (centimeter) divided by hip circumference (centimeter). HOMA-IR was calculated as [FPGxFINS]/22.5 to evaluate the degree of insulin resistance, where FPG was the fasting plasma glucose level (millimole per liter), and FINS was fasting insulin level (milli-international unit per milliliter). 120 cases were divided two groups according to testosterone levels, hypogonadal group andnormal group. 120 cases were divided two groups according to BMI, non-obesity group and overweight or obesity group. All statistical analyses were performed using SPSS 10.0 for Windows. Quantitative data were expressed as mean ± SD, if they were normally distributed. Correlations were assessed using Pearson's method or partial correlation whenever appropriate. Data between groups were assessed using independent-samples T test. P values were two-sided throughout, and that less than 0.05 was considered significant.Results: (1) Of the subjects, 14% were with low levels of total testosterone (TT<2.8ng/ml), 71% had insulin resistance (HOMA-IR=2.8), 52% were overweight or obesity (BMI=23kg/m~2), 18% had hypercholesteremia, 45% had hypertriglyceridemia, 35% had low levels of HDL-C (HDL-C<0.91mmol/L). (2) Correlations: Total testosterone correlated negatively with BMI, FINS and WHR(r=-0.335 for BMI, -0.307 for FINS, and -0.232 for WHR; p<0.01 for BMI and FINS, p<0.05 for WHR). After adjustment for age, duration of diabetes, glucose, insulin and lipid, TT was still correlated strongly and negatively with BMI. After controlling BMI, the relationships between TT, FINS and WHR disappeared. TT correlated positively with apoA-I and HDL-C(r=0.248 for apoA-I, 0.22 for HDL-C; p<0.01 for apoA-I, p<0.05 for HDL-C). After adjustment for BMI, the correlation between TT and apoA-I attenuated (r=0.1906, p<0.05), and the correlation between TT and HDL-C disappeared. But there were no significant associations among TT, age, duration of diabetes, FPG, FINS, FCP, HbA1c, TG, TC, and lnHOMA-IR. BMI was correlated strongly and negatively with age and HDL-C (r=-0.259 for age, r=-0.250 for HDL-C, p<0.01 for both),but with FCP and lnHOMA-IR positively(r=0.356 for FCP, r=0.301 for lnHOMA-IR, p<0.01 for FCP, p<0.05 for lnHOMA-IR). There was a positive relationship between age and gonadotropic hormone, including LH and FSH ( r=0.310 for LH, r=0.442 for FSH, p<0.01 for both). (3) Higher BMI and lower levels of HDL-C, LDL-C, apoA-I were found in hypogonadia group than normal group. And this study showed that overweight or obese patients had lower TT, HDL-C, apoA-I levels and higher WHR, FCP levels than no-obesity patients.Conclusions: Insulin resistance, obesity, dyslipidemia and hypogonadism occur commonly in men with diabetes. Obesity is the main factor of hypotestosteronemia in men with type 2 diabetes. Serum testosterone is correlated with insulin resistance and dyslipidemia. Weight loss may improve the insulin sensitivity and increase the levels of total testosterone in type 2 diabetes.