In India, what is the most common cause of diabetes mellitus in the adult population?

Explanation

## Epidemiology of Diabetes in India **Key Point:** Type 2 diabetes mellitus (T2DM) accounts for approximately 90–95% of all diabetes cases in India and globally. ### Prevalence Data - India has the second-highest number of people with diabetes worldwide (after China), with an estimated 77 million adults affected - T2DM prevalence in urban India ranges from 10–15%, and in rural areas 3–8% - The rising prevalence is driven by urbanization, sedentary lifestyle, dietary changes, and obesity ### Why T2DM Dominates | Feature | Type 1 DM | Type 2 DM | |---------|-----------|----------| | Prevalence in India | 5–10% of all diabetes | 90–95% of all diabetes | | Age of onset | Typically < 30 years | Typically > 40 years | | Pathophysiology | Autoimmune β-cell destruction | Insulin resistance + β-cell dysfunction | | Risk factors | Genetic predisposition, HLA genes | Obesity, sedentary lifestyle, family history | | Geographic variation | More common in Caucasians | More common in South Asians | **High-Yield:** The Indian phenotype of T2DM is characterized by: - Earlier age of onset (mean 40–45 years vs. 55–60 years in Western populations) - Lower BMI at diagnosis ("lean NIDDM") - Higher insulin resistance relative to obesity - Greater cardiovascular risk **Clinical Pearl:** The ICMR-INDIAB study (2015) confirmed that T2DM accounts for > 90% of diabetes burden in India, with a national prevalence of 7.3% in adults. ### Secondary Causes Are Rare - Pancreatitis-related diabetes: < 1% of all diabetes cases - Gestational diabetes: occurs in 3–5% of pregnancies but is not a cause of adult diabetes in the general population - Type 1 diabetes: remains uncommon in South Asian populations compared to Northern European ancestry