Diabetes with low body mass index in India: A secondary analysis of NFHS-5 data

The International Diabetes Federation (IDF) recently recognized "Type 5 Diabetes" ("T5DM") as a distinct entity. Proponents estimate a burden of 6 million cases in India. However, the applicability of this classification in the Indian context, which is dominated by Lean Type 2 Diabetes (T2D), remains debated.

We conducted a secondary analysis of the National Family Health Survey-5 (2019-2021), comprising 788,974 respondents, to estimate the prevalence of young and middle-aged people (15-49 years) with low BMI Diabetes in India. The proxy phenotype was defined as: BMI <18.5 kg/m² (or age-appropriate z-scores for adolescents), and either Fasting Blood Glucose ≥126 mg/dL, Random Blood Glucose (RBG) ≥200 mg/dL, or self-reported diabetes.

The analysis identified 1351 individuals meeting the low BMI diabetes phenotypic criteria. The weighted prevalence of low BMI Diabetes was 0.19 (95 % CI: 0.18 to 0.21). While the raw sample was predominantly female due to survey design, weighted analysis revealed significantly higher prevalence in males (Female: 0.18 vs. Male: 0.25; p = 0.006). Cases were significantly concentrated in the poorest wealth quintiles (54 %), contrasting with the affluent demographic typically associated with T2D. Extrapolating to the national population and adjusting for 50 % undiagnosed cases, we estimate 2.42 million Indians aged <50 years have low BMI diabetes.

The prevalence of "T5DM" is likely to be substantially lower than previous estimates, even after accounting for underdiagnosis. The primary diabetes burden in non-obese Indian adults is likely Lean T2D driven by visceral adiposity rather than malnutrition.