Myopia and Early Onset Type 2 Diabetes: A Nationwide Cohort Study.

OBJECTIVE A correlation between myopia and insulin-resistance has been suggested. We investigated the association between myopia in adolescence and type 2 diabetes (T2D) incidence in young adulthood. DESIGN Population-based, retrospective, cohort study. METHODS 1,329,705 adolescents (579,543 women, 43.6%) aged 16-19 years, medically examined before mandatory military service during 1993-2012; and whose data were linked to the Israel National Diabetes Registry. Myopia was defined based on right eye refractive data. Cox proportional models were applied, separately for women and men, to estimate hazard ratios (HRs) for T2D incidence per person-years of follow-up. RESULTS There was an interaction between myopia and sex with T2D (P<0.001). For women, T2D incidence rates (per 100,000 person-years) were 16.6, 19.2, and 25.1 for those without myopia, and with mild-to-moderate and high myopia, respectively. These corresponded to HRs of 1.29 (95%CI 1.14-1.45) and 1.63 (1.21-2.18) for women with mild-to-moderate and high myopia, respectively, compared to those without myopia, after adjustment for age at study entry, birth year, adolescent BMI, cognitive performance, socioeconomic status, and immigration status. Results persisted in extensive sensitivity and subgroup analyses. When managed as a continuous variable, every 1 diopter lower spherical equivalent yielded a 6.5% higher adjusted HR for T2D incidence (P= 0.003). There was no significant association among men. CONCLUSIONS For women, myopia in adolescence was associated with a significantly increased risk for incident T2D in young adulthood, in a severity-dependent manner. This finding may support the role of insulin resistance in myopia pathogenesis.