At a scientific meeting of the American Diabetes Association this weekend, researchers had some disappointing and some downright confusing news. Two new studies showed that contrary to expectations, drastically cutting blood-sugar levels in diabetic patients did nothing to reduce their risk of heart disease and strokes.
In the most disquieting result, one of the studies was halted early because the patients who were given intensive treatment to lower their blood sugar had a higher death rate. Researchers say they don’t know whether to blame the treatment regimen, a mix of diabetes drugs and insulin, or the patients’ reduced blood-sugar levels. However, the second study showed no similar increase in mortality rates.
The study that showed increased mortality was conducted in the United States, the other in Australia; combined, they tracked about 20,000 patients over several years. Researchers suggested that the disparity may have something to do with the rate at which patients’ reduced their blood-sugar levels. In the American study, patients achieved their low glucose levels within four months, while the Australian patients took a year to reach the same point.
There was one promising result in the Australian study: The patients with very low blood-sugar levels had fewer cases of kidney disease, a common complication of diabetes. Because of the benefits to the kidneys, researchers said it’s too early to dismiss the potential advantages of lowering blood sugar below recommended levels. “Getting down to even lower levels can protect patients from devastating kidney disease,” said Simon Heller, a lead researcher in the Australian study and a diabetes professor at the University of Sheffield. “It could protect 1 in 5 people from kidney disease” [San Francisco Chronicle].
Both were published online in the New England Journal of Medicine. Researchers say the surprising results should influence the advice that doctors give to their patients. “It’s disappointing,” said Stephen MacMahon, a researcher from the George Institute for International Health in Sydney and an author of the [Australian] study. “The message is if you want to change the risk of major macrovascular events, you can’t do it by lowering glucose.” He said controlling blood pressure and lowering cholesterol levels have a much bigger impact on reducing heart-attack and stroke risk.
An accompanying editorial to the studies says rather than considering changes to recommended blood-sugar levels, clinicians should stress other measures to their diabetic patients, such as smoking cessation and improvements in diet and exercise [The Wall Street Journal, subscription required].