Cataracts and glaucoma are also more common among diabetics. It is also important to note that since the lens of the eye lets water through, if blood sugar concentrations vary a lot, the lens of the eye will shrink and swell with fluid accordingly. As a result, blurry vision is very common in poorly controlled diabetes. Patients are usually discouraged from getting a new eyeglass prescription until their blood sugar is controlled. This allows for a more accurate assessment of what kind of glasses prescription is required.
These diabetes complications are related to blood vessel diseases and are generally classified into small vessel disease, such as those involving the eyes, kidneys and nerves (microvascular disease), and large vessel disease involving the heart and blood vessels (macrovascular disease). Diabetes accelerates hardening of the arteries (atherosclerosis) of the larger blood vessels, leading to coronary heart disease (angina or heart attack), strokes, and pain in the lower extremities because of lack of blood supply (claudication).
While there are competing explanations of the link between obesity and type 2 diabetes, Gerald Shulman, MD, PhD, a professor of internal medicine and physiology at Yale University, believes the key is figuring out insulin resistance. He has studied the causes of insulin resistance for 25 years and thinks he may have the answer to the weight-diabetes link.
Some people with type 2 diabetes are treated with insulin. Insulin is either injected with a syringe several times per day, or delivered via an insulin pump. The goal of insulin therapy is to mimic the way the pancreas would produce and distribute its own insulin, if it were able to manufacture it. Taking insulin does not mean you have done a bad job of trying to control your blood glucose—instead it simply means that your body doesn’t produce or use enough of it on its own to cover the foods you eat.
In an otherwise healthy individual, blood glucose levels usually do not rise above 180 mg/dL (9 mmol/L). In a child with diabetes, blood sugar levels rise if insulin is insufficient for a given glucose load. The renal threshold for glucose reabsorption is exceeded when blood glucose levels exceed 180 mg/dL (10 mmol/L), causing glycosuria with the typical symptoms of polyuria and polydipsia. (See Pathophysiology, Clinical, and Treatment.)
The food that people eat provides the body with glucose, which is used by the cells as a source of energy. If insulin isn't available or doesn't work correctly to move glucose from the blood into cells, glucose will stay in the blood. High blood glucose levels are toxic, and cells that don't get glucose are lacking the fuel they need to function properly.
When there is excess glucose present in the blood, as with type 2 diabetes, the kidneys react by flushing it out of the blood and into the urine. This results in more urine production and the need to urinate more frequently, as well as an increased risk of urinary tract infections (UTIs) in men and women. People with type 2 diabetes are twice as likely to get a UTI as people without the disease, and the risk is higher in women than in men.