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Rapid Changes in Serum Testosterone in Men with Newly Diagnosed Type 2 Diabetes With Intensive Insulin and Metformin

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posted on 03.02.2021, 22:09 by Yun Hu, Bo Ding, Yun Shen, Reng-Na Yan, Feng-Fei Li, Rui Sun, Ting Jing, Kok-Onn Lee, Jian-Hua Ma
Objective: To investigate the effect of metformin on testosterone levels in men with type 2 diabetes mellitus (T2DM).

Methods: Seventy men with newly diagnosed drug naïve T2DM, HbA1c >9.0% (75mmol/mol) were treated with intensive insulin pump therapy for 5 days to achieve glucose normalization. They were randomized to control (continued on intensive insulin only) and metformin (plus metformin) groups (1:1) for one month. Testosterone was measured at baseline, randomization, and after one-month treatment.

Results: Total, free and bioavailable testosterone increased significantly within 5 days (all p<0.001). After one month, compared to controls, the metformin group had lower total (12.7 vs 15.3 nmol/L), free (0.20 vs 0.24 nmol/L), and bioavailable (4.56 vs 5.31 nmol/L) testosterone (p all <0.05).

Conclusions: In men with T2DM, one-month oral metformin may decrease serum testosterone levels independent of blood glucose control. The effects of long-term metformin on testosterone in men need further study.


This study was supported by the National Key R&D Program of China (No. 2018YFC1314103), the National Natural Science Foundation of China (No. 81870563) and the Nanjing Municipal Science and Technology Project (No. 201803011).