In the sunshine, molecules in the skin are converted to vitamin D. But people stay indoors more these days, which could lead to vitamin D deficiency. Research shows that if mice are deprived of vitamin D, they are more likely to become diabetic. In people, observational studies have also found a correlation between D deficiency and type 1. "If you don't have enough D, then [your immune system] doesn't function like it should," says Chantal Mathieu, MD, PhD, a professor of experimental medicine and endocrinology at Katholieke Universiteit Leuven in Belgium. "Vitamin D is not the cause of type 1 diabetes. [But] if you already have a risk, you don't want to have vitamin D deficiency on board because that's going to be one of the little pushes that pushes you in the wrong direction."
Diabetes means your blood glucose, or blood sugar, levels are too high. With type 2 diabetes, the more common type, your body does not make or use insulin well. Insulin is a hormone that helps glucose get into your cells to give them energy. Without insulin, too much glucose stays in your blood. Over time, high blood glucose can lead to serious problems with your heart, eyes, kidneys, nerves, and gums and teeth.
Visual impairment and blindness are common sequelae of uncontrolled diabetes. The three most frequently occurring problems involving the eye are diabetic retinopathy, cataracts, and glaucoma. photocoagulation of destructive lesions of the retina with laser beams can be used to delay further progress of pathologic changes and thereby preserve sight in the affected eye.
The glucose level at which symptoms develop varies greatly from individual to individual (and from time to time in the same individual), depending in part on the duration of diabetes, the frequency of hypoglycemic episodes, the rate of fall of glycemia, and overall control. (Glucose is also the sole energy source for erythrocytes and the kidney medulla.)
Medications used to treat diabetes do so by lowering blood sugar levels. There is broad consensus that when people with diabetes maintain tight glucose control (also called "tight glycemic control") -- keeping the glucose levels in their blood within normal ranges - that they experience fewer complications like kidney problems and eye problems. There is however debate as to whether this is cost effective for people later in life.