Diabetes in Older Adults

More than 25% of the U.S. population aged ≥65 years has diabetes, and the aging of the overall population is a significant driver of the diabetes epidemic. Although the burden of diabetes is often described in terms of its impact on working-age adults, diabetes in older adults is linked to higher mortality, reduced functional status, and increased risk of institutionalization. Older adults with diabetes are at substantial risk for both acute and chronic microvascular and cardiovascular complications of the disease.

Despite having the highest prevalence of diabetes of any age-group, older persons and/or those with multiple comorbidities have often been excluded from randomized controlled trials of treatments—and treatment targets—for diabetes and its associated conditions. Heterogeneity of health status of older adults (even within an age range) and the dearth of evidence from clinical trials present challenges to determining standard intervention strategies that fit all older adults. To address these issues, the American Diabetes Association (ADA) convened a Consensus Development Conference on Diabetes and Older Adults (defined as those aged ≥65 years) in February 2012. Following a series of scientific presentations by experts in the field, the writing group independently developed this consensus report to address the following questions:

1. What is the epidemiology and pathogenesis of diabetes in older adults?
2. What is the evidence for preventing and treating diabetes and its common comorbidities in older adults?
3. What current guidelines exist for treating diabetes in older adults?
4. What issues need to be considered in individualizing treatment recommendations for older adults?
5. What are consensus recommendations for treating older adults with or at risk for diabetes?
6. How can gaps in the evidence best be filled?

What is the epidemiology and pathogenesis of diabetes in older adults?

According to the most recent surveillance data, the prevalence of diabetes among U.S. adults aged ≥65 years varies from 22 to 33%, depending on the diagnostic criteria used. Postprandial hyperglycemia is a prominent characteristic of type 2 diabetes in older adults , contributing to observed differences in prevalence depending on which diagnostic test is used . Using the A1C or fasting plasma glucose (FPG) diagnostic criteria, as is currently done for national surveillance, one-third of older adults with diabetes are undiagnosed (1).

The epidemic of type 2 diabetes is clearly linked to increasing rates of overweight and obesity in the U.S. population, but projections by the Centers for Disease Control and Prevention (CDC) suggest that even if diabetes incidence rates level off, the prevalence of diabetes will double in the next 20 years, in part due to the aging of the population . Other projections suggest that the number of cases of diagnosed diabetes in those aged ≥65 years will increase by 4.5-fold (compared to 3-fold in the total population) between 2005 and 2050 .

The incidence of diabetes increases with age until about age 65 years, after which both incidence and prevalence seem to level off . As a result, older adults with diabetes may either have incident disease (diagnosed after age 65 years) or long-standing diabetes with onset in middle age or earlier. Demographic and clinical characteristics of these two groups differ in a number of ways, adding to the complexity of making generalized treatment recommendations for older patients with diabetes. Older-age–onset diabetes is more common in non-Hispanic whites and is characterized by lower mean A1C and lower likelihood of insulin use than is middle-age–onset diabetes. Although a history of retinopathy is significantly more common in older adults with middle-age–onset diabetes than those with older-age onset, there is, interestingly, no difference in prevalence of cardiovascular disease (CVD) or peripheral neuropathy by age of onset .

Older adults with diabetes have the highest rates of major lower-extremity amputation , myocardial infarction (MI), visual impairment, and end-stage renal disease of any age-group. Those aged ≥75 years have higher rates than those aged 65–74 years for most complications. Deaths from hyperglycemic crises also are significantly higher in older adults (although rates have declined markedly in the past 2 decades). Those aged ≥75 years also have double the rate of emergency department visits for hypoglycemia than the general population with diabetes .

Although increasing numbers of individuals with type 1 diabetes are living into old age , this discussion of pathophysiology concerns type 2 diabetes—overwhelmingly the most common incident and prevalent type in older age-groups. Older adults are at high risk for the development of type 2 diabetes due to the combined effects of increasing insulin resistance and impaired pancreatic islet function with aging. Age-related insulin resistance appears to be primarily associated with adiposity, sarcopenia, and physical inactivity, which may partially explain the disproportionate success of the intensive lifestyle intervention in older participants in the Diabetes Prevention Program (DPP) . However, age-related declines of pancreatic islet function  and islet proliferative capacity  have previously been described.