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A Link Between Diabetes and Vitamin D Levels

By Jessica Patella, ND abstracted from “Vitamin D and incidence of diabetes: A prospective cohort study Vitamin D and diabetes incidence.” in the before print 2012 issue of Clinical Nutrition.

Key Words: Diabetes, Vitamin D

Vitamin D deficiency is an important public health problem that is affecting adults in epidemic proportions in Western societies (1). Research has already shown vitamin D has a clear impact on bone metabolism (2). Now a link between vitamin D and cardiovascular health, diabetes, cancer and mortality is emerging (2).

Recent research shows a link between blood levels of vitamin D and the incidence of type 2 diabetes (3). The first phase of the long-term study conducted in Spain involved1226 randomly chosen participants from 1996-1998. Participants were screened for vitamin D levels (serum 25-hydroxyvitamin D) and sugar levels (hemoglobin A1C and oral glucose tolerance test) (3). Of the original group of participants, 988 were reassessed in 2002-2004 for the second phase of the study. The final phase from 2005-2006 assessed the remaining 961 participants (3).

The average age of the participants at the beginning of the study was 50.3 +/- 14.4 years and 57% were women. At the final follow-up, there were 26 new cases of diabetes. Those that developed diabetes had a lower blood level of vitamin D (20.7 +/- 5.8 ng/mL) compared to those that did not develop diabetes (23.3 +/- 6.2 ng/mL; P<0.0001).

The incidence of diabetes in participants with vitamin D levels less than 18.5 ng/mL was 12.4% versus 4.7% of participants with vitamin D levels above 18.5 ng/mL (3). None of the participants with vitamin D levels above 30 ng/mL developed diabetes (3). This shows an inverse relationship between vitamin D levels (serum 25-hydroxyvitamin D) and the incidence of type 2 diabetes (3).

There are a few theories on why vitamin D would have this effect on the development of diabetes. First, vitamin D influences beta cell function. Beta cells are cells in the pancreas that store and release insulin based on blood glucose levels. Secondly, vitamin D can modify insulin sensitivity by increasing insulin receptors on cells. The more insulin receptors that are active on cells, the more glucose enters the cells instead of remaining in the blood. Thirdly, vitamin D lowers overall inflammation in the body and inflammation is linked to multiple diseases, including diabetes (3).

In conclusion, there is a link between low vitamin D levels and the increased risk of developing type 2 diabetes. This long-term study included numerous subjects. Future studies to determine how vitamin D lowers the risk of diabetes still need to be conducted. Diet diaries would also be helpful, since what the participants were eating was not assessed in this study.

Jessica Patella, ND, is a naturopathic physician specializing in nutrition and homeopathic medicine and offers a holistic approach to health. She earned her ND from Southwest College of Naturopathic Medicine in Tempe, AZ, and is a member of the North Carolina Association of Naturopathic Physicians. Visit her website at www.awarenesswellness.com.

REFERENCES:

1. 1. Prentice A. Vitamin D deficiency: a global perspective. Nutr Rev 10 Suppl. 2, 66, S153-164.

2. Holick MF. Vitamin D: extraskeletal health. Endocrinol Metab Clin North Am 2010;39:381e400.

3. Gonzolez-Molero I, et al. Vitamin D and incidence of diabetes: A prospective cohort study. Clinical Nutrition (2012) doi:10.1016/iclnu.2011.12.001