Risk of type 2 diabetes in metabolically healthy people in different categories of body mass index: an updated network meta-analysis of prospective cohort studies

Introduction: Risk of diabetes mellitus type 2 (T2DM) is variable between individuals due to different metabolic phenotypes. In present network meta-analysis, we aimed to evaluate the risk of T2DM related with current definitions of metabolic health in different body mass index (BMI) categories. Methods: Relevant articles were collected by systematically searching PubMed and Scopus databases up to 20 March 2018 and for analyses we used a random-effects model. Nineteen prospective cohort studies were included in the analyses and metabolically healthy normal weight (MHNW) was considered as the reference group in direct comparison for calculating indirect comparisons in difference type of BMI categories. Results: Total of 199403 participants and 10388 cases from 19 cohort studies, were included in our network meta-analysis. Metabolically unhealthy obesity (MUHO) group poses highest risk for T2DM development with 10 times higher risk when is compared with MHNW (10.46 95% CI; 8.30, 13.18) and after that Metabolically unhealthy overweight (MUOW) individuals were at highest risk of T2DM with 7 times higher risk comparing with MHNW (7.25, 95% CI; 5.49, 9.57). Metabolically healthy overweight and obese (MHOW/MHO) individuals have (1.77, 95% CI; 1.33, 2.35) and (3.00, 95% CI; 2.33, 3.85) risk ratio for T2DM development in comparison with MHNW respectively. Conclusion: In conclusion we found that being classified as overweight and obese increased the risk of T2DM in comparison with normal weight. In addition, metabolically unhealthy (MUH) individuals are at higher risk of T2DM in all categories of BMI compared with metabolically healthy individuals.