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.