IntroductionThis study’s objective was to produce robust, comparable estimates of the prevalence of diabetes and pre-diabetes in the Sri Lankan adult population, where previous studies suggest the highest prevalence in South Asia.Research design and methodsWe used data on 6661 adults from the nationally representative 2018/2019 first wave of the Sri Lanka Health and Ageing Study (SLHAS). We classified glycemic status based on previous diabetes diagnosis, and either fasting plasma glucose (FPG), or FPG and 2-hour plasma glucose (2-h PG). We estimated crude and age-standardized prevalence of pre-diabetes and diabetes and by major individual characteristics weighting the data to account for study design and subject participation.ResultsCrude prevalence of diabetes in adults was 23.0% (95% CI 21.2% to 24.7%) using both 2-h PG and FPG, and age-standardized prevalence was 21.8% (95% CI 20.1% to 23.5%). Using only FPG, prevalence was 18.5% (95% CI 7.1% to 19.8%). Previously diagnosed prevalence was 14.3% (95% CI 13.1% to 15.5%) of all adults. The prevalence of pre-diabetes was 30.5% (95% CI 28.2% to 32.7%). Diabetes prevalence increased with age until ages ≥70 years and was more prevalent in female, urban, more affluent, and Muslim adults. Diabetes and pre-diabetes prevalence increased with body mass index (BMI) but was as high as 21% and 29%, respectively, in those of normal weight.ConclusionsStudy limitations included using only a single visit to assess diabetes, relying on self-reported fasting times, and unavailability of glycated hemoglobin for most participants. Our results indicate that Sri Lanka has a very high diabetes prevalence, significantly higher than previous estimates of 8%–15% and higher than current global estimates for any other Asian country. Our results have implications for other populations of South Asian origin, and the high prevalence of diabetes and dysglycemia at normal body weight indicates the need for further research to understand the underlying drivers.