Introduction
Older adults are the fastest growing segment of the population with type 2 diabetes.1 Treatment of diabetes in older adults is complex: this highly heterogeneous group requires individualized consideration of the potential benefits and harms from glycemic treatment.2–4 The benefit of intensive glycemic treatment is prevention of long-term complications, but these protective effects can take years to accrue, with a lag time to benefit of 8–10 years.5–7 In contrast, the harms of intensive glycemic treatment, primarily hypoglycemia and its associated risks, may be immediate. Thus, it is critically important to evaluate remaining life expectancy when weighing the benefits and risks of glycemic treatment for older adults.5 8 For some older adults, the lag time to benefit may extend beyond their remaining life expectancy, resulting in unlikely benefit from treatment while exposing them to potential harms, including hypoglycemia. On the other hand, healthy older adults may live for another 15–20 years, leaving them ample time to benefit from intensive glycemic treatment. Thus, accurate estimates of remaining life expectancy are crucial for individualizing glycemic treatment for older adults with diabetes.
To assist clinicians in determining the appropriate intensity of glycemic treatment for older adults, the American Diabetes Association (ADA) Framework classifies older adults into three categories corresponding to their remaining life expectancy: Healthy, Intermediate/Complex Health, and Very Complex/Poor Health.4 Each group has different treatment goals for blood pressure, statin use, and glycemia, with hemoglobin A1c (HbA1c) goals of <7.5% for Healthy, <8.0% for Intermediate/Complex Health, and <8.5% for Very Complex/Poor Health. These HbA1c goals are based primarily on expert opinion. The categories are assigned using a combination of comorbidities, cognitive abilities, and functional status, as suggested by prior literature.9 10 Life expectancy is explicitly named as the rationale for each category: the Healthy group has ‘longer remaining life expectancy’, while for the Poor Health group, ‘limited remaining life expectancy [making] benefit uncertain’.4
However, there has been no validation of the ADA Framework’s classification by life expectancy: the median life expectancy of each group is unknown. It is thus unclear how effectively the ADA Framework stratifies older adults into categories that correspond to the likelihood of benefit from glycemic treatment. Of note, while age strongly influences estimated life expectancy, the current ADA Framework does not explicitly incorporate age in its classification system.
We sought to validate the ADA Framework’s classification by life expectancy using the Health and Retirement Study (HRS), a nationally representative study of US adults. A priori, we hypothesized that focusing on comorbidities associated with mortality (and ignoring comorbidities not strongly associated with mortality) and accounting for age would improve stratification by life expectancy. Specifically, we modified the ADA Framework by: (1) removing three common comorbidities that are weakly associated with life expectancy (arthritis, hypertension, and incontinence) and (2) stratifying by 5-year age categories. For the original ADA Framework and the modified comorbidity framework, we calculated the percent of older adults in the USA who would be classified as Healthy (likely to benefit from intensive glycemic treatment, target HbA1c <7.5%), Intermediate Health (possible benefit from intensive glycemic treatment, target HbA1c <8.0%), and Poor Health (unlikely to benefit from intensive glycemic treatment, target HbA1c <8.5%). We also calculated the median, 25th and 75th percentiles of life expectancy for each group.