ObjectivesThe burden of diabetes mellitus (DM) has increased globally, particularly in low-income and middle-income countries, including Nepal. Population-based nationally representative data on the prevalence of DM is limited. This paper presents the prevalence of DM and its associated risk factors in Nepal.Research designs and methodsThis population-based study sampled 13 200 participants aged 20 years and above in 400 clusters of 72 districts of Nepal. The study used a standardised questionnaire adapted from the WHO STEPwise approach to non-communicable disease risk factor surveillance instrument and digitalised in Android-compatible mobile phones. Fasting and 2 hours postprandial blood samples were taken to test various biochemical parameters. Descriptive followed by multivariate analyses were done to assess the association between explanatory variables and the outcome variable.Primary outcome measuresPrevalence of DM.ResultsThe prevalence of DM was found to be 8.5% (95% CI 7.8% to 9.3%). The odds of DM occurrence were higher in the upper age groups (40–59 years at adjusted OR (AOR) 3.1 (95% CI2.3 to 4.2) and 60+ years at AOR 4.7 (95% CI 3.3 to 6.6)), compared with the group aged 20–39 years. Men were found to have higher odds of DM (AOR 1.3, 95% CI 1.1 to 1.6) compared with women. Urban residents had almost twice higher odds of DM (AOR 1.7, 95% CI 1.4 to 2.2) compared with rural residents. Participants with raised blood pressure (BP) (AOR 2.2, 95% CI 1.8 to 2.7), those who were overweight and obese (AOR 2.0, 95% CI 1.6 to 2.4) and those who had high triglycride level (≥150 mg/dL) (AOR 2.1, 95% CI 1.8 to 2.6) also had twice higher odds of DM compared with those with normal BP, an average body mass index and normal triglyceride level, respectively.ConclusionsTargeted interventions to higher risk groups as well as prevention and control of other associated biological risk factors might help to reduce the prevalence of DM in Nepal.