Lowering blood sugar levels to near normal through intensive treatment may reduce the risk of cardiovascular disease and heart attacks for Type 2 diabetics, but only if treatment is begun relatively soon after diagnosis and if severe episodes of low blood sugar can be avoided, VA researchers reported Sunday.
The findings from the Veterans Affairs Diabetes Trial may help to resolve concerns raised by two widely reported studies: One found no apparent benefit from such treatment, and the other concluded that intensive treatment might actually be detrimental.
Data from all three studies were presented over the weekend at a San Francisco meeting of the American Diabetes Assn., and although many questions remain unanswered, some generalizations are becoming possible.
Foremost, data from all three studies suggest that the greatest reduction in the risk of heart attacks and cardiovascular disease is achieved by lowering cholesterol levels and by controlling high blood pressure. Controlling glucose can at best provide only a small further reduction in risk that may take many years to become apparent.
But that does not mean that so-called tight control of blood glucose levels is not a good idea. Data from two of the studies confirm earlier findings that such control reduces the risk of kidney and eye disease, also complications of diabetes.
New data from the VA study also show that severe hypoglycemic events -- exceptionally low levels of blood sugar that lead to blackouts or a change of consciousness -- should be avoided at all costs.
The new findings on hypoglycemia may help to explain the sharp differences between the two earlier studies, experts said.
And finally, data from the three studies may ease concerns about the oral diabetes drug rosiglitazone.
An analysis last year of many previous studies suggested that the drug, sold under the brand name Avandia, increases the risk of heart attacks and death.
But the new studies showed no such effects from the drug, which is still in wide use.
Conflicting findings
Researchers have been looking for ways to reduce the cardiovascular risks of diabetes because 65% to 70% of deaths among Type 2 diabetics are caused by heart problems. Studies in Type 1 diabetics, whose pancreases are no longer able to produce insulin, suggest that tight control of glucose levels reduces risks. But studies in Type 2 diabetics, whose bodies become desensitized to insulin and require ever-larger doses, have been more complicated.
