Adolescent Thyroid Disorders and Risk for Type 2 Diabetes in Young Adulthood

Context: Thyroid hormones play a key role in systemic metabolism, yet the relationship between thyroid dysfunction and risk for type 2 diabetes is unclear. Objective: To assess type 2 diabetes risk in adulthood among adolescents with thyroid disorders. Design and Setting: A nationwide, population-based study of Israeli adolescents who were examined before military recruitment during 1988 to 2007 and were followed until December 31, 2016. Participants: 1 382 560 adolescents (mean age 17.3 years). Interventions: The diagnosis of thyroid disorders was based on recent thyroid function tests. Data were linked to the Israeli National Diabetes Registry. Cox proportional hazard models were applied. Main Outcome Measures: Type 2 diabetes incidence. Results: During a mean follow-up of 18.5 years, 1.12% (69 of 6,152) of adolescents with thyroid disorders were diagnosed with type 2 diabetes vs 0.77% of adolescents without thyroid disorders. The hazard ratio (HR) for type 2 diabetes was 2.3 (95% CI, 1.8-2.9) among those with thyroid disorders, after adjustment for sex, birth-year, body mass index, and sociodemographic confounders. The increased diabetes risk was observed in both men and women, with the presence or absence of obesity, and in the absence of other health conditions and was associated with different types of thyroid disorders. It was also similar when the outcome was defined as type 2 diabetes diagnosed at or before the age of 30 years (HR 2.3, 95% CI, 1.5-3.5). Conclusions: Thyroid disorders diagnosed in adolescence are a risk factor for early-onset type 2 diabetes in both men and women.