The 10-year trend of adult diabetes, prediabetes and associated risk factors in Tehran: Phases 1 and 4 of Tehran Lipid and Glucose Study

Abstract

Background: Type 2 diabetes is a global problem with significant morbidity and healthcare costs. In this study, we aimed to determine the 10-year trend of diabetes, prediabetes and their risk factors in the adult urban population of Tehran Lipid and Glucose Study (TLGS).

Materials and methods: In this cross-sectional study, we included all patients above 20 years of age who were registered in phases 1 and 4 of TLGS. Each phase had a 3-year duration. 4580 patients were recruited in each phase (916 patients in each age-group, including 3772 males and 5145 females). Random cluster sampling was used in phase 1 and convenience sampling was used in phase 4. Diabetes and glucose tolerance status were determined according to the 1991 criteria of the American Diabetes Association. In our five age groups, risk factors were compared, which included physical activity, waist circumference, body mass index, education, smoking, lipid profile and family history. Exclusion criteria were placement of an individual in the same age-group in the two phases and pregnancy. We calculated the prevalence of diabetes and dysglycemia in each age-group. Age-specific prevalence rates were determined. Prevalence of risk factors in the two phases were compared using chi-square test and Student t-test. Mann-Whitney U test was used to analyze the variables with non-normal distribution.

Results: In this study, 3976 individuals were recruited in phase 1 (2308 women and 1668 men; female to male ratio 1.38) and 4941 individuals were recruited in phase 4 (2837 women and 2104 men; female to male ratio 1.35). Prevalence of prediabetes in all age groups (except for the 30-39 years age-group) were increased in phase 4 compared to phase 1. Prevalence of known diabetes in all age groups were increased in phase 4 compared to phase 1, yet, the increase was significant only in the 30-39 and 60-69 years age groups (1.8% vs. 0.7% and 19.0% vs. 10.2%, respectively). Newly diagnosed diabetes was decreased in all age groups in phase 4, except for the 60-69 years age-group. The incidence of newly diagnosed diabetes in the 60-69 years age-group was significantly higher in phase 4 compared to the similar age-group of phase 1 (15.2% vs. 11.8%; p<0.001). Physical activity, body mass index, waist circumference (central obesity), general obesity, smoking (except for the 30-39 and 40-49 years age groups), and level of education were significantly higher in phase 4 compared to phase 1. Marriage rates were significantly lower in phase 4 compared to phase 1 across all studied age groups.

Conclusion: We observed an increasing trend in the prevalence of diabetes over a 10-year period in TLGS. This is an accordance with estimates ​​in this field and highlights the need for education, prevention, treatment and control of diabetes. We also found increased rates of central and general obesity, smoking and divorce along with decreased marriage rates, which should be considered by the healthcare policymakers and state health officials as significant risk factors of diabetes.

Keywords: Diabetes; Obesity; Prediabetes; Prevalence.