Diabetes and cardiovascular disease in older adults: current status and future directions

Abstract

The prevalence of diabetes increases with age, driven in part by an absolute increase in incidence among adults aged 65 years and older. Individuals with diabetes are at higher risk for cardiovascular disease, and age strongly predicts cardiovascular complications. Inflammation and oxidative stress appear to play some role in the mechanisms underlying aging, diabetes, cardiovascular disease, and other complications of diabetes. However, the mechanisms underlying the age-associated increase in risk for diabetes and diabetes-related cardiovascular disease remain poorly understood. Moreover, because of the heterogeneity of the older population, a lack of understanding of the biology of aging, and inadequate study of the effects of treatments on traditional complications and geriatric conditions associated with diabetes, no consensus exists on the optimal interventions for older diabetic adults. The Association of Specialty Professors, along with the National Institute on Aging, the National Institute of Diabetes and Digestive and Kidney Diseases, the National Heart, Lung, and Blood Institute, and the American Diabetes Association, held a workshop, summarized in this Perspective, to discuss current knowledge regarding diabetes and cardiovascular disease in older adults, identify gaps, and propose questions to guide future research.

Figure 1

Incidence (per 1,000) of major diabetes complications among adults with diabetes, by age, 2009. Source: National Diabetes Surveillance System, available from http://www.cdc.gov/diabetes. CHF, congestive heart failure; ER, emergency room; ESRD, end-stage renal disease; IHD, ischemic heart disease.

Figure 2

A proposed pathway linking aging, muscle, and risks for diabetes and CVD. Source: Nair KS. Aging muscle. Am J Clin Nutr 2005;81:953–963. T2DM, type 2 diabetes mellitus.

Figure 3

Diabetes incidence rates by age-group in the DPP (36), demonstrating the effectiveness of the lifestyle intervention vs. placebo, especially in the oldest age-group. Reprinted and modified by permission of Oxford University Press on behalf of the Gerontological Society of America.

Figure 4

Relationship between baseline cognitive function and risk for severe hypoglycemia in the ACCORD trial. Kaplan-Meier curves are shown for the proportion of subjects with severe hypoglycemia events according to baseline tertiles of the Digit Symbol Substitution Test (DSST) score. Crude incidence rates and 95% CIs are shown for each group. Log-rank test P = 0.0001. Hazard ratios (HRs) for the middle and highest score groups are with reference to the lowest DSST score group. Patients who scored in the worst tertile on the DSST had the highest rate of severe hypoglycemia, at 2.90%/year or approximately 10% (proportion 0.10) cumulatively over 4 years. The numbers below the x-axis are the actual number of patients in each tertile at each time point (41).

Figure 5

Heterogeneity in health status among patients with diabetes, based on data from the Health and Retirement Study of people over age 50 (48). People with known diabetes were assigned to one of four mutually exclusive categories: a Very Healthy group with no comorbidities; a healthy Intermediate group with comorbidities constrained to osteoarthritis and hypertension, and with no functional impairments; a group for whom intensive diabetes management would be Difficult to Implement due to multiple comorbidities and/or any one of the following: mild cognitive impairment, poor vision, two or more minor functional impairments; and a group with Uncertain Benefit from intensive diabetes management due to having the poorest health status, with one or more of the following: moderate-to-severe cognitive impairment, two or more major functional dependencies, and/or residence in a long-term nursing facility. As the Health and Retirement Study is a U.S. population-based survey, the y-axis estimates the total number of people in the U.S. over age 50 with diabetes in each category.