Question: My 78-year-old-brother has type-2 diabetes. He's at least 20 pounds overweight and doesn't exercise. He claims that he got diabetes from several cortisone shots received many years ago. Is that possible?

Answer: Steroids definitely can cause and worsen diabetes - especially when taken by mouth or by injection for extended periods. But I doubt that a remote history of a few cortisone injections, presumably for bursitis or arthritis, is the reason he became a diabetic. The amount and duration of steroid exposure don't seem sufficient.

Steroids can potentially cause diabetes because they work in opposition to insulin, the hormone that normally lowers the body's level of blood sugar. This can create insulin resistance and a tendency for blood sugars to rise - in essence, what type-2 (also known as adult-onset) diabetes is about. Steroids cause the liver to make more glucose (sugar), and they cause muscle, bone, protein, and lymphatic tissue to be broken down into proteins that are subsequently funneled to the liver to produce even more glucose. What's more, steroids cause the pancreas to make glucagon, a hormone that raises blood sugar. Steroids, especially when taken by mouth, will stimulate appetite, encourage weight gain, and increase the risk of diabetes.

The most likely cause of your brother's diabetes is his gradual weight gain, likely due to a combination of age, less physical activity, and increased caloric consumption. Let's face it - it's tough to lose weight when arthritis or other illness limits your ability to get around. He should check his thyroid function, since a sluggish thyroid makes losing weight harder.

My suggestions: Make sure he's on a diabetic diet that controls both carbs and calories. A registered dietician at a local hospital can be a great resource. And the American Diabetes Association posts lots of helpful suggestions at www.diabetes.org.

Daily exercise is difficult but also important for weight control and overall conditioning. Home exercises - stretching and light weight lifting, for example - are helpful. Low-impact exercises like swimming and water aerobics are great; the local senior center or Y may offer programs. Drugs like metformin and Byetta are effective at increasing the body's sensitivity to insulin and might help facilitate weight loss.

Insulin itself becomes necessary only when a combination of several diabetic pills proves inadequate.

A visual impairment that worsens with age

A: People with aniridia are born with eyes that lack an iris, which is the colored part that opens and closes to control the amount of light that can enter. It's congenital, hereditary, and often associated with severe loss of vision.

Most children with aniridia are legally blind, and their vision worsens with age. That's because there's not only a lack of iris development, but also a failure of proper retinal and optic nerve development. There may be corneal changes and development of cataracts, and glaucoma may also worsen vision loss. People with aniridia also have nystagmus, which are unintentional and uncontrollable jittery eye movements that make it still more difficult to see.

Aniridia is present in roughly 1 out of every 90,000 people in the United States. In two-thirds of cases, other family members have it, too. More information is posted by the Aniridia Foundation International at www.aniridia.net.