Cardiovascular disease and diabetes.

Mortality and morbidity in diabetes Peter Savage (Ellicott City, MD) discussed secular trends in cardiovascular disease (CVD) among patients with diabetes. Two-thirds to three-quarters of patients with diabetes will eventually die of CVD. Diabetes is becoming more important as a cause of CVD in the population because of its increasing prevalence, due to the high incidence in minority populations and the increasing obesity of the population. The “key question,” Savage stated, is whether persons with diabetes are different from those without diabetes in not enjoying the same decline in CVD that has been seen in the overall population over the past 50 years, presumably reflecting a variety of advances in the treatment of risk factors. In a study of time trends in mortality in U.S. adults between surveys in 1971–1975 and in 1982–1984, diabetic men had a decline of 13% in age-adjusted CVD mortality, while that for nondiabetic men was 36%, and diabetic women had an increase of 23%, while women without diabetes had a decline in CVD mortality of 27% (1). Although microvascular disease is relatively specific for diabetes, macrovascular disease appears as an acceleration of the illness seen in persons without diabetes. High LDL is a risk factor in those with and without diabetes, but persons with diabetes tend to have low HDL, high triglyceride, and abnormal LDL particle size. They have the hypertension of the insulin resistance syndrome, which becomes exacerbated with renal disease (and diabetic patients with renal disease have extraordinarily high rates of CVD). Diabetes is associated with coagulation abnormalities and inflammation, as well as hyperglycemia, glycation, and secondary effects on CVD risk factors. Insulin resistance and hyperinsulinemia are additional factors in persons with diabetes. Savage pointed out that persons with diabetes and CVD have poorer overall prognosis, with poorer short-term survival, increased risk of recurrent disease, poorer response to surgery, and increased risk of congestive heart failure (CHF). There are particular problems in minority populations, whose CVD rates appear to be increasing, with diabetes a more important risk factor in these groups. Data are, however, somewhat limited and longitudinal follow-up is particularly difficult to obtain, particularly in view of changing diagnosis and treatment of diabetes and risk factors and given the new classification criteria. In the Framingham Heart Study, assessment of the relative CVD risk of those with diabetes compared with those without in 1956, 1966, 1972, and 1979 suggests little relative change at approximately twice the level seen in nondiabetic individuals. Other studies have shown, however, that death rates from CVD in the U.S. from 1985 to 1999 have declined in nondiabetic men and women in most ethnic groups, though to varying degrees, while there may be an increase in CVD in American Indian populations, perhaps in association with their high prevalence of diabetes. The effects of treatment of patients with diabetes with statins are similar to those for nondiabetic groups. Blood pressure lowering also appears to convey similar relative benefit to patients with and without diabetes. Thus, CVD risk factor treatment is at least as effective as it is in persons without diabetes, although the greater absolute risk of diabetic subjects gives them greater absolute benefit from the interventions. One difficulty may be that patients with diabetes require such a great deal of preventive treatment; subsequently, their rates of compliance with recommended treatment may be lower than desirable. The Cardiovascular Health Study showed that rates of glucose, blood pressure, and lipid control, and of aspirin administration for older persons with diabetes, are less likely to be at goal than for those without diabetes (recognizing that goals are stricter for persons with diabetes) (2). Savage concluded that there is only limited evidence that patients with diabetes are benefiting less from the decline in CVD, and that there are some unique aspects of CVD in persons with diabetes that require particular attention. He stated that the “benefit of controlling hyperglycemia on CVD risk remains to be proven,” although he believed it was an appropriate goal. He pointed out the importance of aggressive control of known risk factors, the need for heightened provider awareness and effort, and the need for improved health care system support. Steven Haffner (San Antonio, TX) discussed the primary prevention of CVD in patients with type 2 diabetes. (For a summary of this presentation, see http://diabeteshighlights.org/summary/ summary.asp?sid 1&stid 15&ld 2002-06-17.) Levels of prevention can be classified as primary prevention of diabetes itself, secondary prevention of complications in diabetic subjects free of disease, and tertiary prevention of further complications in those persons with diabetes who already have evidence of CVD. Haffner pointed out that there is high outof-hospital mortality before first myocardial infarction in men with diabetes (3) and increased CVD prior to the onset of type 2 diabetes (4), suggesting that the truly appropriate approach should be diabetes prevention rather than frequent screening and treatment of those persons who have evidence of CVD. Prevention studies include the Da Qing Study (showing 31–46% risk reduction), the Finnish Prevention Study (showing 58% risk re● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●