Guidelines for treating diabetes mellitus are mostly based on clinical studies in middle-aged people, and recommendations tend to be the same for everyone, whether young and strong or elderly and frail. But diabetes management should be individualized, especially in the elderly, taking into account each patient’s medical history, functional ability, home care situation, and life expectancy. Aggressive glycemic control is less important than avoiding hypoglycemia and achieving a good quality of life.
This article reviews the general principles for recognizing and managing diabetes in elderly patients, focusing on the management of blood sugar per se. In a future issue of this journal, we will discuss some of the many complications of diabetes in the elderly.
DIABETES DIFFERS IN ELDERLY PATIENTS
“The elderly” is a heterogeneous group with widely varying physiologic profiles, functional capabilities, and life expectancy (on average, about 88 years for men and 90 years for women in the United States). Although the elderly are sometimes classified as “young-old” (age 65–80) and “old-old” (80+), this distinction is too simplistic for clinical decision-making.
Diabetes mellitus in the elderly also is heterogeneous. One distinction is the age at which the disease developed.
Aging is associated with declining beta-cell function and lower blood insulin levels independent of insulin resistance, and with insulin resistance itself. The risk of developing type 2 diabetes mellitus increases with obesity, lack of physical activity, and loss of muscle mass, all of which often develop with aging.1
Middle-aged patients with diabetes have increased fasting hepatic glucose production, increased insulin resistance, and an abnormal insulin response to a glucose load. On the other hand, patients who develop diabetes at an older age tend to have normal hepatic glucose production. Older patients who are lean secrete markedly less insulin in response to a glucose load but have relatively less insulin resistance.2 Patients who develop type 2 diabetes in old age are more likely to have near-normal fasting blood glucose levels but significant postprandial hyperglycemia.3,4 Elderly patients who developed diabetes during middle age have metabolic abnormalities more typical of middle-aged patients with type 2 diabetes.
DIABETES IS COMMON, AND INCREASING IN PREVALENCE
By age 75, 40% of people in the United States have either glucose intolerance or diabetes mellitus.5 Metabolic syndrome, which is the constellation of insulin resistance (type 2 diabetes mellitus), hyperlipidemia, hypertension, and obesity, is more prevalent in people age 65 to 74 years than in younger and older people.3
The National Diabetes Surveillance System of the US Centers for Disease Control and Prevention estimated that the prevalence of diabetes mellitus in people 65 to 74 years old in 2005 was 18.5%, about 12 times the prevalence among those younger than 45years.6 The prevalence has been gradually increasing and has nearly doubled over the past 25 years, with certain groups—native Americans, Hispanics, and African-Americans—at particularly high risk of developing the disease.
Although the prevalence of diabetes in people older than 75 years is lower than among people in the 65-to-74-year range, the elderly segment of our population is increasing, and the impact of diabetes and its associated burden of death and disease from vascular complications is enormous.
SYMPTOMS ARE OFTEN NONSPECIFIC
Unfortunately, diabetes is underdiagnosed and frequently undertreated, resulting in even more disease and death.7–9
Diabetes is often missed in the elderly because its presenting symptoms may be nonspecific, eg, failure to thrive, low energy, falls, dizziness, confusion, nocturia (with or without incontinence), and urinary tract infection.The classic symptoms of frequent urination (often leading to worsening incontinence), thirst, and increased hunger usually occur only when plasma glucose levels are above 200 mg/dL. Weight loss, blurred vision, and dehydration may also be present with high blood glucose levels. With lesser degrees of hyperglycemia, patients may have no symptoms or present with weight loss or signs and symptoms of chronic infection, especially of the genitourinary tract, skin, or mouth.
Hyperglycemia in elderly patients is also associated with reduced cognitive function (which may improve with blood glucose control).10
The American Diabetes Association recommends screening by measuring the fasting plasma glucose level every 3 years beginning at 45 years.11 However, some experts believe that this method is inadequate for the elderly12; some suggest that screening should be done more often in those with risk factors for diabetes, including obesity, inactivity, hypertension, and dyslipidemia, all of which are common in the elderly. Targeted screening in patients with hypertension may be the most cost-effective strategy.13
Screening with hemoglobin A1c levels is not recommended because of lack of standardization among laboratories.14