The Association Between Body Mass Index and Glycemic Control in Patients with Type 2 Diabetes Across Eight Countries: A Literature Review

Objectives: To investigate the association between obesity and glycemic control based on country-specific glycemic control data from the USA and selected European and Asian countries by body mass index (BMI), or BMI data by glycemic control (HbA1c), in individuals with type 2 diabetes (T2D). Methods: Literature search of databases and abstracts to identify real-world studies (2015-2020) reporting HbA1c and BMI data. Results: Seventeen articles (China, including Hong Kong, n=10; Japan, n=3; USA, n=2; Spain, n=1; UK, n=1) were identified from 6696 de-duplicated references. Of the 13 studies reporting by BMI mean rates of glycemic control or likelihood of achieving glycemic control, eight found that achieving control significantly declined as BMI increased; one reported a clear trend but no statistics; two reported glycemic control rates for those with obesity to be significantly worse than for one other group; and two reported no significant difference with BMI. Of the six studies reporting average HbA1c levels by BMI, four reported HbA1c to increase with BMI. Two of three studies reporting mean BMIs by glycemic control found these increased with HbA1c. Conclusions: This review consolidates recent evidence on the glycemic control status of individuals with T2D reported by BMI in selected countries. Studies generally reported a lower chance of achieving glycemic control targets in those with overweight or obesity. Most studies found greater HbA1c in individuals with higher BMI, and average BMI greater in those with higher levels of HbA1c. Focused efforts are needed to improve glycemic control in patients with T2D and overweight/obesity.