Vitamin D is an interesting compound. First, by strict definition it’s not a vitamin. A vitamin is something that can’t be “manufactured” in your body, and must be acquired in diet. But, you can make vitamin D by exposing your bare skin to sunlight. The questions are how much can you make, and how much is metabolically available. Sunscreen, dark skin, northern climates, and winter make manufacturing lots of vitamin D very challenging. Excess body fat, which can sequester the fat soluble vitamin, may compromise the availability of vitamin D in your metabolism.
Vitamin D deficiency is associated with diabetes in ways that aren’t fully understood. Some evidence hints that inadequate vitamin D is associated with the onset of type 1 diabetes. People with type 2 diabetes, especially women, show higher levels of vitamin D deficiency.
Now a small study suggests that raising vitamin D levels among 100 type 2 diabetes patients by supplementing with vitamin D3 over an 8 week period significantly lowered fasting blood glucose levels, and the effect was most significant when the blood level of the active form of vitamin D was between 40 and 60 nanograms per milliliter. This level is considerably higher than the recommended minimum level, and supplementation isn’t a “straight line” benefit.
Even without regard for the potential benefit to blood glucose levels, knowing your current level of vitamin D is important. Ask your doctor to authorize the blood test, and discuss supplementation for all the potential benefits.