The Relationship Between Vitamin D and Insulin Resistance

Uncovering the impact of vitamin D deficiency on diabetes has been a full-time job. Past research has concluded that there is no connection when it comes to type 2 diabetes, but another study showed that children with type 1 diabetes have a higher risk of lacking vitamin D. Researchers have taken another crack at understanding the potential link better with a new study presented at the American Diabetes Association (ADA 2016) 76^th Scientific Sessions in New Orleans, Louisiana.

A team from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) — apart of the National Institutes of Health (NIH) – aimed to identify the role of vitamin D in insulin resistance. The researchers noted that past observational studies determined that there is link, however, interventional studies concluded the opposite.

African Americans are 1.7 times more likely to have diabetes than Caucasians, and are significantly more likely to have additional disease-related problems such as blindness and kidney disease. So the NIDDK researchers used a cohort including 90 healthy African descent women — 36 African American and 54 African immigrant.

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The average participant was 41 years old with a body mass index (BMI) of 29.6 and 38% body fat. The average total 25-hydroxyvitamin D (25-(OH)D) was 21 ng/mL, but 43 of the participants had levels less than 20, which is clinically categorized as deficient.

Based off of the fasting plasma glucose (FPG) test and 2-hour glucose tolerance test (GTT), 30 of the women were considered pre-diabetic. The homeostatic model assessment (HOMA) and Matsuda Index determined insulin resistance levels.

Overall, both the African American and African immigrant participants had similar 25-OHD concentrations and the measures didn’t vary whether they had prediabetes or not. In addition, as weather plays a role in vitamin D levels, this study did not find seasonal impact on the DC-based population.

“The relationship of total 25-OHD with measures of insulin sensitivity did not differ by ethnicity and was mediated by adiposity,” the authors explained.

Therefore, it was concluded that vitamin D does not play a role insulin resistance — in the African American female population, anyway.

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