High prevalence of type 2 diabetes and pre-diabetes in adult Zoroastrians in Yazd, Iran: a cross-sectional study

BACKGROUND: The prevalence of type 2 diabetes mellitus (T2DM) varies among ethnic groups. We aimed to estimate the prevalence of diagnosed and undiagnosed diabetes mellitus, impaired fasting glucose (IFG), and impaired glucose tolerance (IGT) for the first time in an ethnic population, specifically Zoroastrian citizens in Yazd, Iran whose ages were 30 or older. METHODS: In a cross-sectional study, participants aged≥30 years were selected using systematic random sampling. An inventory, including socio-demographic data, was completed. Weight, height, body mass index (BMI), and blood pressure (BP) were measured using standard methods. Also, blood levels of glucose, triglycerides (TG), total cholesterol (TC), high density lipoprotein (HDL), low density lipoprotein (LDL), urea, creatinine (Cr), and uric acid were measured. The latest criteria established by the American Diabetes Association (ADA) were used to diagnose DM. RESULTS: The mean age of the participants (n=403) was 56.9±12.8 years. The total prevalence of diabetes, including previously diagnosed and undiagnosed diabetes, IFG, and IGT was 26.1%, 18.6%, 7.5%, 34.7% and 25.8%, respectively. Participants with diabetes had higher fasting blood sugar (FBS) (P<0.001), oral glucose tolerance test (OGTT) (P<0.001), urea (P=0.019), BMI (P=0.001), systolic blood pressures (P<0.001), TG (P=0.007) and lower HDL (P=0.034) than patients with IFG, IGT, and normoglycemic subjects. CONCLUSIONS: The current study showed a high prevalence of T2DM in the Zoroastrian population of Yazd, Iran. One-third of the total cases with diabetes were undiagnosed.