The Gonadal Hormone Regulates the Plasma Lactate Levels in Type 2 Diabetes Treated With and Without Metformin

Objective: Our previous study showed there was a gender difference in plasma lactate concentrations in subjects with type 2 diabetes. This study investigated the effect of sex hormone levels on plasma lactic acid (LA) levels in type 2 diabetes with and without metformin therapy. Subjects and Methods: Fasting whole blood specimens of 392 type 2 diabetes patients treated with metformin (n=199) or not (n=193) were collected. LA was measured with an enzyme-electrode assay. Levels of sex hormones, including testosterone (T) and estradiol (E-2), were measured with a chemiluminescence microparticle immunoassay. Spearman's or Pearson's correlation and logistic regression analysis were performed for the factors associated with LA. Results: The LA level in the metformin group was significantly higher than that in the non-metformin group (1.26+/-0.43 vs. 1.14+/-0.49 mmol/L, P<0.001), and LA levels of females were significantly higher than those of males (P<0.001). LA concentrations were positively correlated with E-2 level but negatively correlated with metformin and T levels (P<0.01). The logistic regression analysis showed that gender, creatinine, E-2, metformin, and T were independent factors influencing lactate levels. Analysis of subgroups demonstrated that the LA concentrations increased with the elevation of E-2 level (P<0.05) but decreased with the rising of T level (P<0.05). Conclusions: Sex hormones play an important role on regulating plasma lactate levels in diabetes patients treated with metformin. E-2 up-regulates but T tend to down-regulate lactate levels.