Alendronate improves fasting plasma glucose and insulin sensitivity and decreases insulin resistance in prediabetic osteopenic postmenopausal women: a randomized triple-blind clinical trial

Aims Postmenopausal women receive bisphosphonates for osteoporosis treatment. The effect of these medications on developing diabetes mellitus (DM) in prediabetic patients is yet to be investigated. We aimed to determine the effect of alendronate on plasma glucose, insulin indices of postmenopausal women with prediabetes and osteopenia. Methods This triple‐blind randomized controlled clinical trial included 60 postmenopausal women, aged 45–60 years. All patients were vitamin D sufficient. They were randomly enrolled in intervention (70 mg/week alendronate for 12 week) and control (placebo tablet per week for 12 weeks) groups. The morning 8 hour fasting blood samples were collected at the baseline and follow–up visits to measure the fasting plasma glucose (FPG) (mg/dl), insulin and hemoglobin A1c (HbA1c). Plasma glucose and insulin concentration were measured 30, 60, and 120 minutes after glucose tolerance test. Matsuda index, homeostasis model assessment of insulin resistance (HOMA–IR), homeostasis model assessment of beta–cell function (HOMA–B) and the area under the curves (AUC) of glucose and insulin were calculated. Results Mean (SD) FPG (102.43 (1.46) mg/dl vs. 94.23)1.17) mg/dl, P=0.001), 120‐minutes insulin concentration (101.86)15.70) mU/l vs. 72.60 (11.36), P=0.026), HbA1c (5.60 (0.06) % vs. 5.40 (0.05)%, P=0.001), HOMA‐IR (3.57 (0.45) vs. 2.62 (0.24), P=0.021) and Matsuda index (7.7 (0.41) vs. 9.2 (0.4), P=0.001) significantly improved in the alendronate‐treated group. There was statistically significant more reductions in FPG (‐8.2 (8.63) mg/dl vs. ‐2.5 (14.26) mg/dl, P=0.002) and HbA1c (‐0.2 (0.23) % vs. ‐0.09 (0.26) %, P=0.015) were observed in alendronate‐treated group than placebo group during the study course, respectively. Conclusions Administration of 70 mg/week alendronate improves fasting plasma glucose, HbA1c and insulin indices in postmenopausal women.