Tuesday, May 29, 2012

Vitamin D , insulin secretion and insulin resistance

Vitamin D , insulin secretion and insulin resistance

 The mechanisms driving the association between Vitamin D and insulin secretion and insulin resistance is not understood. There are a number of " maybe's " and a few studies.

 Vitamin D  "may " influence and may directly stimulate insulin secretion function and may reduce insulin resistance by the effects of intracellular calcium on insulin receptors.

A few of the few studies

 Diabetes med.2009Jan (1) : 19-27 found vitamin  D3 supplement improved after meal insulin sensitivity in non-diabetic obese males

Int.J. clin Pract. 2003may ; 57 (4) :258-61 evaluated 10 females with Type 2 diabetes and low vitamin D levels. They were treated for 1 month with Vitamin D supplement  and found that 70 % achieved normal vitamin D levels and a 21% decrease in insulin resistance that was not statistically significant.  Their study suggest that  Vitamin D deficiency  " may " contribute to the impairment of insulin secretion and insulin action . "our  results suggest that Vitamin D 3 supplement could be an element in the complex treatment of type 2 diabetes during the winter " Diabetes Care. 2011 May;34(5):1114-9. Epub 2011 Mar 23.

Serum 25-hydroxyvitamin d levels and prediabetes among subjects free of diabetes.
Department of Community Medicine,West Virginia University School of Medicine, Morgantown, West Virginia, USA. ashankar@hsc.wvu.edu
Animal studies suggest that low serum 25-hydroxyvitamin D (25[OH]D) may impair insulin synthesis and secretion and be involved in the pathogenesis of diabetes. Results in studies in humans have not been consistent, however. Prediabetes is a stage earlier in the hyperglycemia/diabetes continuum where individuals are at increased risk of developing diabetes and where prevention efforts have been shown to be effective in delaying or preventing the onset of diabetes. However, previous studies have not examined the association between low serum 25(OH)D levels and prediabetes.
We examined the 12,719 participants (52.5% women) in the third National Health and Nutrition Examination Survey aged >20 years who were free of diabetes. Serum 25(OH)D levels were categorized into quartiles (≤ 17.7, 17.8-24.5, 24.6-32.4, >32.4 ng/mL). Prediabetes was defined as a 2-h glucose concentration of 140-199 mg/dL, or a fasting glucose concentration of 110-125 mg/dL, or an A1C value of 5.7-6.4%.
Lower serum 25(OH)D levels were associated with prediabetes after adjusting for age, sex, race/ethnicity, season, geographic region, smoking, alcohol intake, BMI, outdoor physical activity, milk consumption, dietary vitamin D, blood pressure, serum cholesterol, C-reactive protein, and glomerular filtration rate. Compared with quartile 4 of 25(OH)D (referent), the odds ratio of prediabetes associated with quartile 1 was 1.47 (95% CI 1.16-1.85; P = 0.001 for trend). Subgroup analyses examining the relation between 25(OH)D and prediabetes by sex, BMI, and hypertension categories also showed a consistent positive association.
Lower serum 25(OH)D levels are associated with prediabetes in a representative sample of U.S. adults.

My thoughts
I think it is reasonable to talk to your doctor about  having a 25- hydroxyvitamin D   ( 25[oh]D ) level tested. My wife has prediabetes  and had a low 25 hydroxyvitamin D level . She  now takes a vitamin D3 supplement and is trying to get a little more Oregon sun.  She plans to recheck the test on her next doctor visit.

Have fun , Be smart and consider a testing your Vitamin D level
David Calder, MD
 tomorrow Vit D and HDL cholesterol

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Your comments and questions are appreciated. David Calder,MD