Optimal control of glucose, blood pressure, LDL cholesterol, and smoking in adults with diabetes could result in substantial reductions of cardiovascular risk, according to results from a large cohort study of diabetes patients with and without underlying cardiovascular disease.
CV events and deaths associated with inadequate control of any of these four modifiable risk factors were about 11% and 3%, respectively, for subjects with baseline CVD, and 34% and 7%, respectively, for those without it.
Though risk was much higher for those with CVD, as expected, more attention to these traditional CVD risk factors in all diabetic patients – with or without CVD – would significantly reduce CVD-related morbidity and mortality, investigators concluded.
For their research, published online in Diabetes Care, epidemiologist Gabriela Vasquez-Benitez, Ph.D., of the Health Partners Institute for Education and Research in Minneapolis and her associates identified 859,617 patients with diabetes (31% with CVD) receiving treatment at a network of 11 U.S. health centers for 6 months or more, with mean follow-up of 5 years. About half of patients were female, and 45% were white. Risk factors were defined as LDL-C ≥100 mg/dL, glycosylated hemoglobin (HbA1c) ≥7%, blood pressure ≥140/90 mm Hg, or smoking.
Dr. Vasquez-Benitez and associates used a regression analysis to quantify the contributions each risk factor made to CVD risk and type of CV event in both patient groups.
In patients without CVD (n = 593,167), the vast majority had HbA1c, BP, and LDL-C not at goal or were current smokers. Inadequately controlled LDL cholesterol was associated with 19.6% of myocardial infarction or acute coronary syndrome (95% confidence interval, 18.7-20.5), and 13.7% of strokes. Smoking was associated with 3.8% of all CV events, while inadequately controlled blood pressure was associated with 11.6% of strokes. Dr. Vasquez-Benitez and colleagues found an increased CV risk for HbA1c above 9%, but no increased risk for HbA1c of 7%-7.9%, compared with 6.5%-6.9%. This finding supports current guidelines recommending HbA1c targets below 7% or 8% for patients with diabetes, according to the investigators (Diab. Care 2015 Feb. 20 [doi:10.2337/dc14-1877]).
In subjects with diabetes and CVD, 7% of stroke was found attributable to inadequate blood pressure control and 5.9% to poor glycemic control. Smoking was the only factor seen associated with an increase in all-cause mortality in this patient group, with 2.6% of deaths seen linked to smoking.
Dr. Vasquez-Benitez and her colleagues noted in their analysis that a substantial share of risk could not be attributed to the modifiable factors investigated in their study, raising the possibility that “unidentified genetic, metabolic, or psychosocial risk factors may affect risk.”
The investigators noted as limitations of their study the fact that risk factors and comorbidities were assessed at baseline and may have changed during follow-up, and that data were obtained from routine care settings with varying time intervals. Patients with type I diabetes may have been included in the cohort due to difficulties distinguishing diabetes types in patient records, they said.
The study was funded by the Agency for Healthcare Research & Quality. None of its authors reported conflicts of interest.