Atherosclerotic Vascular Disease and Diabetes in the Older Adult; Part I: Understanding Pathogenic Mechanisms
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RS is a 75-year-old Caucasian man with essential hypertension and type 2 diabetes mellitus of 7 years duration. He denies diabetic complications and takes only glipizide and atenolol. Physical exam shows weight 218 pounds, height 70”, body mass index 31, blood pressure 152/82 mm Hg, and absent reflexes at the ankles. Patients such as RS, who represent a common office scenario, raise several important questions regarding appropriate treatment:
• What are the risk factors for atherosclerotic vascular disease (ASVD) in this patient?
• Could he already have subclinical disease?
• How does diabetes contribute to the progression of atherosclerosis?
• As a patient in his 8th decade, can he still benefit from aggressive treatment of multiple risk factors, including improved glycemic control, or is it too late?
This article summarizes the current evidence regarding these questions, and provides the clinician with recommendations for preventing and treating macrovascular disease in older persons with diabetes.
Currently, there are 8.6 million Americans, 18.3% of adults, 60 years or older with diabetes.1 An additional 42% of adults over age 60 have the metabolic syndrome and/or prediabetes, both of which often precede the development of overt diabetes and indicate an atherosclerotic milieu associated with increased macrovascular risk.2 Given the aging of our population, the increased prevalence of being overweight or obese, and the age-related body composition changes leading to increased insulin resistance and type 2 diabetes, it is not surprising that cardiovascular disease (CVD) is the leading cause of diabetes-related deaths, with rates 2-4 times higher than in adults without diabetes.1 Together, heart disease and stroke account for 65% of deaths in older persons with diabetes.1 When diagnosed with diabetes at 60 years of age, life expectancy in men is reduced by 7.3 years and in women by 9.5 years.3,4
Although diabetes is strictly defined by plasma glucose levels, it is also a vascular disease, with the vasculature representing the “target organ” for accelerated atherosclerosis.5-8 Given that this process diffusely affects the arterial system, a patient with diabetes and CVD may be expected to have coexistent peripheral vascular disease (PVD), cerebrovascular disease, and/or an abdominal aortic aneurysm. The powerful influence of diabetes on accentuated atherosclerosis was demonstrated in the landmark study by Haffner and colleagues,9 which showed that the incidence of first myocardial infarction (MI) after 7 years of follow-up in patients with type 2 diabetes was the same (20%) as the incidence of MI in patients without diabetes who had had a previous MI (19%). Because of these observations, the Third Report of The National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (ATP III) reclassified diabetes as a coronary heart disease (CHD) equivalent in the highest risk category.10
Older patients with diabetes are particularly clinically challenging, as they represent a heterogeneous population with differences in functional status as well as in duration, severity, and complications of diabetes.11 Added to the challenge of how to prioritize care for individuals such as RS is the recognition that ASVD in older adults is often clinically silent. Using a composite index of noninvasive methods from different arterial vascular beds, the overall prevalence of subclinical ASVD in adults 65 years and older was 37%.12 As shown by Chaves and colleagues,12 subclinical vascular disease increases with age and is at least as prevalent as clinically recognized disease.
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