AUTHOR=Cai Tingting , Hu Yun , Ding Bo , Yan Rengna , Liu Bingli , Cai Ling , Jing Ting , Jiang Lanlan , Xie Xiaojing , Wang Yuming , Wang Huiying , Zhou Yunting , He Ke , Xu Lan , Chen Liang , Cheng Cheng , Ma Jianhua 

TITLE=Effect of Metformin on Testosterone Levels in Male Patients With Type 2 Diabetes Mellitus Treated With Insulin

JOURNAL=Frontiers in Endocrinology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2021.813067

DOI=10.3389/fendo.2021.813067

ISSN=1664-2392

ABSTRACT=<sec><title>Aim</title><p>To explore the chronic effects of metformin on testosterone levels in men with type 2 diabetes mellitus (T2DM).</p></sec><sec><title>Methods</title><p>This is a secondary analysis of a real-world study evaluating the efficacy and safety of premixed insulin treatment in patients with T2DM <italic>via</italic> 3-month intermittent flash glucose monitoring. Male patients aged 18-60 who were using metformin during the 3-month study period were included as the metformin group. The control group included males without metformin therapy by propensity score matching analysis with age as a covariate. Testosterone levels were measured at baseline and after 3-month treatment.</p></sec><sec><title>Results</title><p>After 3-month treatment, the control group had higher levels of total testosterone, free and bioavailable testosterone than those at baseline (P&lt;0.05). Compared with the control group, the change of total (-0.82 ± 0.59 vs. 0.99 ± 0.59 nmol/L) and bioavailable (-0.13 ± 0.16 vs. 0.36 ± 0.16 nmol/L) testosterone levels in the metformin group significantly decreased (P=0.036 and 0.029, respectively). In Glycated Albumin (GA) improved subgroup, the TT, FT, and Bio-T levels in the control subgroup were higher than their baseline levels (P &lt; 0.05). Compared with the metformin subgroup, TT level in the control subgroup also increased significantly (P=0.044). In GA unimproved subgroup, the change of TT level in the metformin subgroup was significantly lower than that in the control subgroup (P=0.040).</p></sec><sec><title>Conclusion</title><p>In men with T2DM, 3-month metformin therapy can reduce testosterone levels, and counteract the testosterone elevation that accompanied with the improvement of blood glucose.</p></sec><sec><title>Clinical Trial Registration</title><p><uri xlink:href="https://www.clinicaltrials.gov/ct2/show/NCT04847219?term=04847219&amp;draw=2&amp;rank=1" xmlns:xlink="http://www.w3.org/1999/xlink">https://www.clinicaltrials.gov/ct2/show/NCT04847219?term=04847219&amp;draw=2&amp;rank=1</uri>.</p></sec>