Effect of green tea extract on bone turnover markers in type 2 diabetic patients; A double- blind, placebo-controlled clinical trial study

Background and the purpose of the study: This study was performed to investigate the effect of green tea extract (GTE) on bone turnover in type 2 diabetes mellitus (T2DM) patients.Methods: Totally 72 T2DM patients with stratified randomize method were divided into two interventional and control groups in a double blind placebo- control clinical trial study. GTE, 500mg, and placebo were prescribed three times a day for 8 weeks. Laboratory and anthropometric measurements included fasting blood glucose (FBG), oral glucose tolerance test (G2h), glycosylated hemoglobin A1c (HbA1C) and lipid Profile, fasting serum osteocalcin, crosslaps and insulin, body mass index (BMI) and waist to hip ratio (WHR) before and after intervention.Results and major conclusion: Assess of GTE effect on the bone markers revealed that change in osteocalsin was almost significant but log osteocalsin had significant alteration in GTE group. We found no significant changes in WHR, BMI, FBG, G2h, Hb1Ac, fasting insulin concentration and crosslaps levels in this group after intervention. Representational evidences demonstrated that decrease in crosslaps level was 10 times in green tea groups compared to the placebo group. Results also showed that improved bone turnover patients had significantly lower FBG and HbA1c levels ratio than non-improved patients as well as had higher fasting insulin concentration in GTE group.Our results suggest that GTE may reduces bone resorption marker more than placebo and probably modifies the bone turnover in T2DM patients.