Diagnosing Diabetes in the Elderly

By Alan L. Rubin

The incidence of diabetes in the elderly (which is almost always type 2 diabetes) is higher for many reasons, but the main culprit seems to be increasing insulin resistance with aging. Half of the elderly population has prediabetes.

A study in Diabetes Care in August 2008 suggests that the increased insulin resistance associated with aging is due to exactly the same causes as that found in younger people, namely physical inactivity and obesity. However, as a result of decreasing height with age, the body mass index (BMI) isn’t a good indicator of obesity in the elderly. The waist circumference is better. A BMI of 30 may not indicate the same level of increased risk of a heart attack in an elderly person as it does in a younger person. A BMI of 30–35 is associated with only a slight increase in risk. The pancreas seems to be able to make insulin at the usual rate. The fasting blood glucose actually rises very slowly as you get older. The glucose after meals, however, rises much quicker and leads to the diagnosis.

Because the fasting blood glucose is usually normal, the hemoglobin A1c is used to make the diagnosis in the elderly population. A hemoglobin A1c that is above 6.5 percent is considered diagnostic of diabetes. Results that fall between normal and that value are in a gray zone that probably indicates prediabetes.

The Diabetes and Aging Study (Diabetes Care, June 2011) showed that a hemoglobin A1c of 8 percent was associated with the lowest rates of complications and death in older diabetic patients while a level of less than 6 percent was associated with higher death rates.

Elderly people with diabetes often don’t complain of any symptoms. When they do, the symptoms may not be the ones usually associated with type 2 diabetes, or they may be confusing. Elderly people with diabetes may complain of loss of appetite or weakness, and they may lose weight rather than become obese. They may have incontinence of urine, which is usually thought of as a prostate problem in elderly men or a urinary-tract infection in older women. Elderly people with diabetes may not complain of thirst because their ability to feel thirst is altered.