Harvard Heart Letter

Ask the doctor: Why does diabetes raise heart disease risk?

Q. I just got diagnosed with diabetes and my doctor said I am at risk for heart disease. Why?

A. Diabetes is considered to be an extremely strong risk factor for heart disease. One reason is that people with diabetes are also more likely to have other conditions that raise their odds of heart disease, such as obesity, high blood pressure, or elevated LDL cholesterol. Also, those factors seem to have more of a detrimental effect on people who have diabetes compared with those who don't.

The reasons why aren't completely clear, but high blood sugar (the hallmark of diabetes) seems to harm blood vessels in several different ways. It damages the tissue that lines the inner walls of the arteries, a process that encourages the buildup of cholesterol-laden plaque. And that plaque seems to be more prone to rupture, potentially triggering a blockage that leads to a heart attack. Excess sugar also coats circulating cells in the blood, making them sticky and more likely to form clots. Finally, high sugar levels lower levels of nitric oxide, a powerful blood vessel–widening chemical made naturally by the body. If your blood vessels stay constricted rather than relaxed, you're more likely to have blood flow problems.

To continue reading this article, you must login.
  • Research health conditions
  • Check your symptoms
  • Prepare for a doctor's visit or test
  • Find the best treatments and procedures for you
  • Explore options for better nutrition and exercise
Learn more about the many benefits and features of joining Harvard Health Online »