Are active sun exposure habits related to lowering risk of type 2 diabetes mellitus in women, a prospective cohort study?

Abstract

Aim An inverse relationship exists between vitamin D levels and diabetes mellitus. However, little is known about the correlation of sun exposure habits and type 2 diabetes mellitus (DM). Methods A South Swedish cohort study comprising 1000 women from each age group between 25 and 64 ( n = 40,000) drawn from the Southern Swedish population registry 1990–1992. At the inception of the study 74% answered the inquiry ( n = 29,518) and provided detailed information on their sun exposure habits and other variables. A follow-up inquiry was sent 2000–2002 which 24,098 women answered. The mean follow-up time was 11 years. Logistic regression analysis was used and the main outcome was the relationship between type 2 DM and sun exposure habits. Results Our findings indicated that women with active sun exposure habits were at a 30% lower risk of having DM, as compared to those with non-active habits. There was an inverse relation between this risk reduction and BMI. Conclusion Our investigation gives possible epidemiological explanation to ethnic and seasonal differences in type 2 DM and metabolic control. The study supports that sunlight is involved in the glucose metabolism.