Age- and sex-related prevalence of diabetes mellitus among immigrants to Ontario, Canada

Regarding the prevalence of diabetes mellitus among immigrants to Ontario, as observed by Creatore and colleagues [1], it may be useful to obtain the prevalence of vitamin D deficiency/insufficiency in the studied population. There is evidence in the published literature that individuals with inadequate vitamin D status are more likely to be obese or overweight [2, 3, 4]. Further, obesity is associated with an increased risk of developing diabetes [5, 6], and studies show that low vitamin D may impair insulin action and glucose metabolism [7, 8].

Vitamin D is synthesized in the skin through an ultraviolet (UV-B) radiation induced photosynthetic reaction, where the efficiency of production is impacted by clothing, excess body fat, sunscreen, and the skin pigment melanin [9]. People in the tropical regions have adapted to an intense solar irradiation by developing darker skin pigmentation [10], which protects them from potentially harmful effects of excessive UV- doses. However, this becomes a disadvantage when they migrate to higher latitudes where the annual solar irradiation is not sufficient for them to synthesize physiologically required quantities of vitamin D, leading to a potentially severe deficiency [11, 12].

Vitamin D status could play a role in the observed increased prevalence of diabetes mellitus among the immigrants from South Asia, the Caribbean, South America and Africa (i.e., darker skin migrants from lower to higher latitudes). Hence, community-level educational programs on diabetes may need to include recommendations on an adequate diet and vitamin D supplementation to prevent severe essential micronutrient deficiencies, particularly among the immigrants from tropical regions.

Goran Krstić, B.Sc., Ph.D., R.P.Bio.

Fraser Health, New Westminster, BC

REFERENCES

1. Creatore MI, Moineddin R, Booth G, et al. Age- and sex-related prevalence of diabetes mellitus among immigrants to Ontario, Canada. CMAJ 2010;DOI:10.1503/cmaj.091551 (early release).

2. Rodríguez-Rodríguez E, Navia B, López-Sobaler AM and Ortega RM. Vitamin D in overweight/obese women and its relationship with dietetic and anthropometric variables. Obesity 2009;17(4):778-782.

3. Aasheim ET, Hofsø D, Hjelmesæth J, et al. Vitamin status in morbidly obese patients: a cross-sectional study. Am J Clin Nutr 2008;87(2):362-369.

4. Foss YJ. Vitamin D deficiency is the cause of common obesity. Med Hypothesis 2009;72(3):314-321.

5. Lau DC. Diabetes and weight management. Prim Care Diabetes 2010;4S1:S24-S30.

6. Papandreou D, Malindretos P, Karabouta Z, and Rousso I. Possible health implications and low vitamin D status during childhood and adolescence: An updated mini review. Int J Endocrinology 2010; doi:10.1155/2010/472173.

7. McGill AT, Stewart JM, Lithander FE, et al. Relationships of low serum vitamin D3 with anthropometry and markers of the metabolic syndrome and diabetes in overweight and obesity. Nutrition 2008;7:4.

8. Schwalfenberg G. Not enough vitamin D: Health consequences for Canadians. Can Fam Physician 2007;53:841-854.

9. Mead MN. Benefits of sunlight: A bright spot for human health. Environ Health Persp 2008;116(4):A160-A167.

10. Jablonski NG and Chaplin G: The evolution of human skin coloration. J Hum Evol 2000, 39:57–106.

11. Hintzpeter B, Scheidt-Nave C, Müller MJ, Schenk L, and Mensink GBM: Higher prevalence of vitamin D deficiency is associated with immigrant background among children and adolescents in Germany. J Nutr 2008;138:1482–1490.

12. Genuis SJ, Schwalfenberg GK, Hiltz MN and Vaselenak SA. Vitamin D status of clinical practice populations at higher latitudes: Analysis and applications. Int J Environ Res Public Health 2009;6:151-173.

Conflict of Interest:

None declared