Legume consumption and its association with fasting glucose, insulin resistance and type 2 diabetes in the Indian Migration Study

Objective: Legume consumption is associated with lower fasting glucose (FG) and insulin levels in nutrition trials and lower CVD mortality in large-scale epidemiological studies. In India, legumes are widely consumed in various preparations, yet no epidemiological study has evaluated the association of legumes with FG levels, insulin resistance and diabetes risk. The present study aimed to fill this gap. Design: Fasting blood samples, in-person interviews to obtain information on demographic/socio-economic factors, physical activity, alcohol and tobacco use, and anthropometric measurements were collected. Dietary intakes were assessed by an interviewer-administered, validated, semi-quantitative FFQ. Setting: Lucknow, Nagpur, Hyderabad and Bangalore, India. Subjects: Men and women (n 6367) aged 15-76 years - urban residents, urban migrants and their rural siblings. Results: In multivariate random-effects models adjusted for age, BMI, total energy intake, macronutrients, physical activity and rural/migration status, daily legume consumption was not associated with FG (P-for-trend = 0.78), insulin resistance (homeostasis model assessment score; P-for-trend = 0.73) or the prevalence of type 2 diabetes mellitus (P-for-trend = 0.41). Stratified analyses by vegetarian diet and migration status did not change the findings. Inverse associations between legumes and FG emerged for participants with lower BMI and higher carbohydrate, protein, fat and sugar intakes. Conclusions: Although legumes are essential in traditional Indian diets, as well as in prudent and Mediterranean diets in the West, we did not find an association between legumes and markers of glycaemic control, insulin resistance or diabetes, except for subgroups based on BMI and macronutrient intake. The ubiquitous presence and complexity of legume preparations in Indian diets may contribute to these findings.