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Low Vitamin D and Type 2 Diabetes

Nov 22, 2013

How do vitamin D levels correlate with HbA1c?… 

Recent studies have demonstrated correlations between low vitamin D levels and the development of type 2 diabetes while others provide similar findings but on the opposite spectrum where higher levels of vitamin D are associated with decreased incidence of type 2 diabetes. Additionally, previous research identified vitamin D receptors in the β cells of the pancreas and linked vitamin D to insulin secretion regulation.

A new study aimed to show a correlation between glycemic control and levels of vitamin D (25-hydroxy vitamin D3) in type 2 diabetic patients. This study looked at 25(OH) D3 and HbA1C levels of 120 persons with type 2 diabetes aged 25 – 82 years old and compared them to 120 similar aged control subjects without diabetes. A1C levels were higher in the diabetes group as expected (7.2 ± 0.18% versus 5.1 ± 0.05%) and the vitamin D3 levels were significantly lower in the diabetes group as compared to the control group (19.26 ± 0.94 ng/ml and 25.48 ± 1.02 ng/ml; p<0.001). The researchers further analyzed vitamin D levels in the diabetes vs. healthy control group and found that 17.5% (21/120) and 63.3% (76/120) of the persons in the diabetes group were vitamin D deficient and insufficient, respectively, as compared to 5.8% (7/120) and 23.3% (28/120) of the control group participants with a C2 p value=0.0089 and p < 0.0001, respectively. Linear regression analysis of HbA1C levels vs. vitamin D levels showed an inverse relationship.

This study shows a fairly strong correlation between vitamin D deficiency/insufficiency and type 2 diabetes and also demonstrates a negative correlation between vitamin D levels and HbA1C. Findings from this study suggest we should be monitoring vitamin D levels in persons with type 2 diabetes and providing vitamin supplementation to those in which it is clinically warranted.

Practice Pearls:

  • Vitamin D receptors are present in the β cells of the pancreas and vitamin D has been linked to insulin secretion regulation.
  • Vitamin D levels may have an inverse relationship with HbA1C and low levels of vitamin D show a correlation to increased incidence of type 2 diabetes.
  • Vitamin D supplementation should be considered in those with type 2 diabetes when clinically indicated

Kostoglou-Athanassiou, I. et al. Vitamin D and Glycemic Control in Diabetes Mellitus Type 2. Therapeutic Advances in Endocrinology and Metabolism. 2013;4(4):122-128