The big story this year was the relationship between blood glucose control and cardiovascular health in people with type 2 diabetes, with the presentation of long-awaited findings from three major clinical trials known as ACCORD, ADVANCE, and VADT.

Since people with diabetes are at increased risk for heart disease, each study was examining whether it could better be prevented with “intensive” glucose lowering, to near normal, nondiabetic levels, rather than a less rigorous approach. Earlier studies have already established that tight control of blood glucose—in both type 1 and type 2—helps prevent or delay the microvascular complications of diabetes, like retinopathy (diabetic eye disease) and nephropathy (diabetic kidney disease).

In these latest trials, however, it turned out that intensive therapy didn’t reduce cardiovascular risk significantly more than standard therapy did in the types of people studied. Still, researchers continue to derive other, more promising insights about diabetes care from the studies.

The ADVANCE trial studied the cardiovascular health effects of lowering blood pressure and blood glucose in people 55 and older, with type 2 diabetes and a history of either cardiovascular or microvascular disease or at least one risk factor for a vascular disease. The blood pressure component ended in 2007 and found a significant benefit to getting people’s blood pressure to even lower levels than currently recommended targets. The blood glucose segment randomized patients to either a standard target (based on local guidelines) or an intensive target (A1C less than or equal to 6.5 percent). The standard group could be treated with any drug except for gliclazide, a sulfonylurea, while the intensive group was required to begin treatment with gliclazide and then add in any other medication as necessary to achieve the target. Although no difference in risk for cardiovascular disease was found, the study identified a 14 percent reduction in microvascular complications with intensive therapy, mostly due to a re­duction in diabetic kidney problems.

The VADT sought to determine the effects of intensive glucose control on cardiovascular risk in people with type 2 diabetes. In this study, the participants, all over age 40, were selected on the basis of having poor glucose control, with A1Cs over 7.5 despite maximum doses of one or more oral medications, and/or insulin. The intensive target was an A1C of less than 6 percent, while the standard target was between 8 and 9 percent. Doctors could use their choice of drugs. Both groups of VADT participants were encouraged to take aspirin and quit smoking, and were strictly treated for high blood pressure or cholesterol. Not only did this allow the researchers to attribute any differences in cardiovascular disease (CVD) rates to differences in blood glucose control, but aggressive control of these important risk factors may also help explain the lower-than- expected number of cardiovascular events in the study. Cardiovascular events were slightly lower in the intensive glucose treatment arm, but the result was not conclusive.

The ACCORD study compared intensive versus standard therapy for three facets of treatment—blood glucose, blood pressure, and cholesterol—in people with type 2 diabetes and either established CVD or risk factors for developing it. The intensive group aimed for an A1C level below 6 percent; the standard arm had a target A1C between 7 and 8 percent. Again, doctors were free to use any drug combination to achieve these targets.