by Bruce Sylvester – The combination of obesity and low vitamin D deficiency appears to cause a greater risk of insulin resistance than either factor alone, researchers reported on July 17 online in Diabetes Care.
“Vitamin D insufficiency and obesity are individual risk factors for insulin resistance and diabetes,” said lead author Shaum Kabadi, a doctoral candidate in epidemiology at Drexel University School of Public Health in Philadelphia, Pennsylvania. “Our results suggest that the combination of these two factors increases the odds of insulin resistance to an even greater degree than would have been expected based on their individual contributions.”
As background, the authors noted that the body stores vitamin D in adipose fat, rendering it unusable, and overweight persons are already more likely to have low levels of serum vitamin D.
Kabadi, Liu and colleagues analyzed data from 5,806 respondents to the National Health and Nutrition Examination Survey (NHANES), a large, US study of the association between vitamin D and diabetes risk for obese patients.
The investigators found that obese subjects with healthy levels of vitamin D had insulin resistance about 20 times more often than the overall study population. In obese individuals with low serum vitamin D, insulin resistance was 32 times higher than that of the overall study population.
Senior author Dr. Longjian Liu, an associate professor in the School of Public Health, noted, “It’s not clear whether obesity itself causes a low vitamin D level or if it’s the other way around.”
The authors concluded that more research could show if vitamin D supplements effectively reduce the risk of insulin resistance and diabetes in obese individuals. If so, they said that it could become an inexpensive and practical prevention strategy.