Intensive glycemic control and cardiovascular risk

This review explored whether strict glycemic control can reduce the risk of cardiovascular events among diabetic patients.

Hyperglycemia, or high blood glucose levels, can damage both large and small blood vessels. Damage to large blood vessels significantly elevates the risk for complications such as heart attacks or strokes (referred to collectively as cardiovascular events). Research has shown that adequate control over blood pressure, blood glucose levels and cholesterol levels may reduce the risk of mortality by up to 50% and the risk of cardiovascular events by up to 60%. However, how intensively blood glucose levels should be controlled is still a matter of some debate. While the American Diabetes Association recommends maintaining an HgbA1c level (a measurement of average blood glucose levels) of 7% or less, some studies have suggested that more intensive glycemic control, to an HgbA1c level of 6.5% or 6%, may significantly benefit patients.

Three major trials were conducted in recent years that directly compared standard glycemic control to more intensive therapy. None of the studies managed to demonstrate a reduction in the risk of mortality with more intensive glycemic control. One of the studies did demonstrate a 24% reduction in the risk of non-fatal heart attacks with intensive glycemic control (to a target HgbA1c level of 6%). However, the same study also showed a significant increase in early mortality within the first few years of intensive therapy.

An analysis of all three studies, including a total of 27,049 patients, showed that compared to standard control, intensive therapy regimens lead to a 15% reduction in the risk of non-fatal heart attacks, a 9% reduction in the risk of all cardiovascular events (including strokes), but no benefit to the risk of early mortality.

A sub-analysis of the trial results showed that younger patients, and those managing diabetes for less than 12 years, are most likely to benefit from intensive glycemic control. Intensive therapy in patients managing diabetes for more than 16 years was associated with worse prognosis.

This review concluded that intensive blood glucose control may reduce the risk of cardiovascular events, specifically early in the management of the disease. No survival benefit was demonstrated with intensive therapy.