Diabetes Equalizes Heart Disease Risk Among Men and Women

Study finds that younger and middle-age women with diabetes have similar heart disease risk factors as men—a 4-fold increase compared to women without diabetes. Aggressive screening and treatment urged.

Premenopausal women are typically at lower risk for coronary artery disease (CAD) than men of the same age. However, new findings suggest that younger women who have diabetes have an approximately 4-fold increased risk for the disease, making it roughly equal to men's risk of this disease.

The findings, reported online ahead of print in Diabetes Care, showed that diabetes had little to no effect on the risk of CAD in men, which was already high even in the absence of diabetes.

"Our findings suggest that we need to work harder to prevent heart disease in women under 60 who have diabetes," said lead author Rita Rastogi Kalyani, MD, MHS, endocrinologist at the Johns Hopkins University School of Medicine in Baltimore, Maryland. " This study tells us that women of any age who have diabetes are at a high risk for CAD," she said.

"In general, people who have diabetes are classified as having the same overall risk for CAD as someone who has known CAD," commented Tara Narula, MD, FACC, Associate Director, Cardiac Care Unit Lenox Hill Hospital/North Shore LIJ, in New York, NY and a member of the American Heart Association Advocacy Committee. " Thus, we need to be more aggressive in treating our diabetes patients in general and specifically, as this study points out, we probably need to be more aggressive in how we treat younger women with diabetes," Dr. Narula said.

Younger Women With Diabetes Should Receive Statins
The findings are timely given the American Heart Association's updated guidelines on treating high cholesterol levels. One of the four groups that the new guidelines recommend is statin therapy for includes people with Type 1 or Type 2 diabetes who are 40 to 75 years old with a low-density lipoprotein cholesterol level of 70 to 189 mg/dL.

"This study looked at women younger than 60, so certainly women with diabetes who are between 40 and 60 years old should be treated with cholesterol lowering medications and specifically with a statin class of agent based on the new guidelines," Dr. Narula said.

The question remains whether physicians should target cholesterol levels in women with diabetes in their 20s and 30s, she added. While this practice is not recommended in the guidelines, the decision may be made on an individualized basis until more information is available, Dr. Narula said.

Findings Based on Three Large Cohorts
The study involved data from more than 10,000 participants(age < 60 years) in 3 large studies: the GeneSTAR Research Program, the Multi-Ethnic Study of Atherosclerosis, and the National Health and Nutrition Examination Survey (NHANES) III. None of the participants had a history of heart disease at baseline. All three studies yielded similar gender differences in rates of diabetes and the risk of developing heart disease.

As expected, among subjects without diabetes, the rate of CAD was significantly lower among women than men. In contrast, in subjects with diabetes, CAD rates were similar among women (range, 2.37-17.65/1,000 person years) and men (1.83-12.86/1,000 person years; P>0.05). Even after adjusting for demographics, the CAD rate was 4-fold higher among women with diabetes than among women without this disease, with no differences found among men with or without the disease.

Interestingly, in both women and men, these findings were unrelated to differences in obesity and other traditional cardiovascular risk factors such as high blood pressure, cholesterol, and smoking.

What Causes This Increased CAD Risk in Younger Women?
Possible causes of this increased risk include different genetic and hormonal factors related to the development of CAD by gender, the authors noted. In addition, differences in adherence to lifestyle behaviors, medication compliance, and intensity of diabetes treatment between genders are also possible causes, but further research is needed, Dr. Kalyani said. Also, the relationship of diabetes duration and glucose control to the risk of heart disease remains unclear.

Reducing CAD Risk in Younger Women With Diabetes
Aggressive treatment should involve treating all of the risk factors for CAD, Dr. Narula said. The first step is to control blood sugar and hemoglobin A1C as well as possible. "The recommendation for A1C level is < 7% and we know that the lower you push it, the better it is for heart health. For each 1% decrease in A1C level equals an almost 40% decrease in the rate of microvascular events," she said.

"Secondly we know that elevated blood pressure confers a higher risk for cardiovascular events and therefore diabetics should be treated to 130/80 mmHg and should be monitored very carefully," Dr. Narula said. Other steps include cholesterol management as already described, smoking cessation, and counseling on weight loss and exercise.

Kalyani RR, Lazo M, Ouyang P, et al. Gender differences in diabetes and risk of incident coronary artery disease in healthy young and middle-aged adults. Diabetes Care. 2013 Oct 31. [Epub ahead of print]

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