The association between ultraviolet B irradiance, vitamin D status and incidence rates of type 1 diabetes in 51 regions worldwide.
OBJECTIVE
This study is an analysis of the relationship between ultraviolet B (UVB) irradiance, the primary source of circulating vitamin D in humans, and age-standardised incidence rates of type 1 diabetes mellitus in children, according to region of the world.


METHODS
The association of UVB irradiance adjusted for cloud cover to incidence rates of type 1 diabetes in children aged <14 years during 1990--1994 in 51 regions worldwide was assessed using multiple regression. Incidence data were obtained from the Diabetes Mondial Project Group.


RESULTS
Incidence rates were generally higher at higher latitudes (R2 = 0.25, p < 0.001). According to multiple regression, UVB irradiance adjusted for cloud cover was inversely associated with incidence rates (p < 0.05), while per capita health expenditure (p < 0.004) was positively associated (overall R2 = 0.42, p < 0.0001).


CONCLUSIONS
An association was found between low UVB irradiance and high incidence rates of type 1 childhood diabetes after controlling for per capita health expenditure. Incidence rates of type 1 diabetes approached zero in regions worldwide with high UVB irradiance, adding new support to the concept of a role of vitamin D in reducing the risk of the disease.
Department of Family and Preventive Medicine, University of California San Diego, 9500 Gilman Drive, Mail Code 0631C, La Jolla, CA 92093-0631, USA.
S B
SB
Mohr
C F
CF
Garland
E D
ED
Gorham
F C
FC
Garland
D000293:Adolescent; D002112:Calcifediol / Q000627:therapeutic use; D002648:Child; D003922:Diabetes Mellitus, Type 1 / Q000150:complications / Q000453:epidemiology* / Q000517:prevention & control; D005843:Geography; D006801:Humans; D012044:Regression Analysis; D014466:Ultraviolet Rays; D014807:Vitamin D / Q000627:therapeutic use*; D014808:Vitamin D Deficiency / Q000150:complications / Q000453:epidemiology
D014807:Vitamin D; D002112:Calcifediol