My sister (age 76), has Type 2 diabetes. Could this cause her constant severe fatigue?

Patient: Until the past couple of years she was very active, but the fatigue prevents her from exercise, she says. She also has much stiffness in her body and joints. N.B: This is really my sister, living in California; not me. I live in NYC and see her only once or twice a year, and I get worried.

Doctor: Well controlled diabetes should not cause constant severe fatigue. This should be evaluated further by doing blood test. She should have her hemoglobin checked, her thyroid function checked. These are the first two tests that I would like to do in her case.

Regards