Score yet one more in favor of having fun in the sun. A new study indicates that lack of vitamin D may be a major factor in the development of diabetes, and as you probably know, sunshine provides one of the best sources of vitamin D. The research, which comes from Johns Hopkins University School of Medicine in Baltimore, found a startling correlation between Type 2 diabetes and lack of vitamin D. Of the 124 diabetic subjects aged 36 to 89 in the study, more than 91 percent were found to be vitamin D deficient or insufficient. Plus, the severity of the deficiency correlated to the severity of the diabetes. In other words, the more deficient the subjects were, the more out-of-control their diabetes was.
Both the director of the study, Dr. Esther Krug, and her colleagues nationwide warned the public not to jump to the conclusion that a vitamin D shortage leads to diabetes. Dr. Krug said, "Our study could not show cause and effect." She points out that people who have developed diabetes may simply neglect their health in general, foregoing sunshine and outdoor exercise, which could contribute to their vitamin D deficiency. Dr. Ritchie Mathur, M.D. of the Cedars-Sinai Medical Center in Los Angeles concurs: "At present," she says, "a direct link between vitamin D and Type II diabetes is not conclusively established. One important point that is missing... is the prevalence of vitamin D deficiency in the general population, compared to those in the study."
Here's the thing. Studies have shown the prevalence of vitamin D deficiency in the general population to be around 36 percent. But the prevalence among diabetic subjects is so much higher -- almost 200 percent higher -- that a link between diabetes and vitamin D look plausible, in spite of the reticence among the scientists to admit it. In fact, seemingly practicing doublespeak, Dr. Krug also said, "This finding supports an active role of vitamin D in the development of Type 2 diabetes...Since primary care providers diagnose and treat most patients with Type 2 diabetes, screening and vitamin D supplementation as part of routine primary care may improve health outcomes of this highly prevalent condition."
The study also found that the hemoglobin A1c value was higher in subjects with lower vitamin D levels. This inverse relationship was even more pronounced among patients of color than among whites. Hemoglobin A1c (HbA1c) indicates how well the body controls blood sugar levels. It is a measure of the blood glucose concentration over the most recent 30 to 120 days. The higher the levels of HbA1c, the more sugar the red blood cells have been exposed to. So in other words, low vitamin D levels seem to have led to poor control of blood sugar levels over time.
Meanwhile, over in Holland, another study also found a link between vitamin D and diabetes, plus, it confirmed that vitamin D may play a role in developing metabolic syndrome. In that study, which followed 1300 subjects, all over the age of 65, about half had vitamin D deficiency, a percentage that still exceeds that found in the general population. Plus, 37 percent had metabolic syndrome, meaning that they had hypertension, high cholesterol, high blood sugar levels, and abdominal obesity -- a constellation of factors considered precursors to both heart problems and diabetes.
I've written before about the profound health implications of vitamin D deficiency -- beyond diabetes and skeletal problems. As I've said, vitamin D deficiency has been implicated in the development of various cancers, cardiovascular disease, psoriasis, Lupus, multiple sclerosis, osteoporosis, arthritis, lupus, and liver, and kidney disease. A new study this year, out of Loyola University, found that vitamin D deficiency may even lead to depression over the dark winter months, and likewise, supplementing with vitamin D may lift mood.
The moral of the story seems fairly obvious. Get enough vitamin D. It can't hurt to supplement with 1000 to 2000 IU of vitamin D3 daily (taken with your largest meal), and it may even pay to have your blood levels of vitamin D tested, even if you assume you're fine because you frolic in the sun every day. In fact, a study of vitamin D levels in Hawaii in 2007 found that 51 percent of the 93 subjects were vitamin D deficient, even though these subjects had abundant exposure to sunlight year-round. The study authors wrote, "These data suggest that variable responsiveness to UVB radiation is evident among individuals, causing some to have low vitamin D status despite abundant sun exposure." Or perhaps, they were just using too much sunscreen.