Background: Type-2 diabetes mellitus (DM) is one of the leading lifestyle-related chronic disease as its prevalence is expected to rise up to 24.0% in the world by 2025, which was only 6.3% in year 2003.

Objective: To understand the high-altitude and low-altitude differentials for DM and diabetic retinopathy (DR) prevalence in a sub-Himalayan state of North India.

Methods: The study was carried out in the Shahpur block of Kangra district (altitude 2,404 feet) and the Spiti block of Lahaul and Spiti district (altitude 12,500 feet) of Himachal Pradesh.

Results: Among diabetics, the prevalence of DR was observed to be high (18.1%) in low landers and low (5.0%) in high landers. DM was more of a problem among low landers with a prevalence of 12.3% when compared to high landers (7.2%). Overall, the odd ratio of DR was twice as high (2.2; 95% confidence interval [CI]: 1.1-2.3) among patients with an unsatisfactory level of HbA1c (>8.0%) adjusted for gender, age group, smoking status and hypertension.

Conclusion: Differential did exist, as DM and DR were significantly lower in high-altitude areas when compared to low-altitude areas.