The ongoing epidemic of diabetes mellitus in India: genetics or lifestyle?

India is estimated to have the second highest number of cases of diabetes mellitus in the world after China. Recent epidemiological evidence indicates that people of lower socioeconomic group in India are equally or even more susceptible to diabetes. Family history is a very strong risk factor for developing type 2 diabetes mellitus; the lifetime risk is nearly 40% for individuals who have one parent affected and approaches 70% if both parents are affected. Genome-wide association studies identified more than 50 genetic variants associated with type 2 diabetes mellitus, but these risk alleles identified to date could only explain less than 10% of the observed heritability. Acquisition of the same unhealthy lifestyle from the parents could be the major reason for the observed heritability that genetics could not explain. The global age-standardised prevalence of diabetes has nearly doubled since 1980, rising from 4.7 to 8.5% in the adult population. If genes are responsible for this doubling of prevalence, the responsible gene pool should also amplify to the same extent in the population. The Hardy–Weinberg law states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences, making genetics as the etiology for this ongoing epidemic less likely. Indians have a tendency to become metabolically obese and develop type 2 diabetes mellitus with normal weight; thus, body mass index cut-off for overweight and obesity is kept lower in Indians. Primary and secondary prevention strategies should be more emphasised at the community level. Physical activity recommended is at least 150 min/week. All adults should decrease the amount of time spent in daily sedentary behaviour. Dietary modifications by reducing carbohydrate intake and increasing the intake of proteins, green leafy vegetables, fruits, and nuts should be promoted.