Doctors already knew that tight control of blood sugar levels is an effective method of preventing cardiovascular and other complications of Type 1 diabetes. But the situation is more complicated for Type 2, which affects the vast majority of the 24 million diabetics in the United States.
Researchers and clinicians had always believed that aggressively lowering sugar levels is beneficial, until two major studies released last year muddied the waters.
One of the trials, called Action to Control Cardiovascular Risk in Diabetes or ACCORD, suggested that aggressively lowering blood sugar caused a 20% increase in deaths, possibly from increased episodes of hypoglycemia, or subnormal blood sugar levels.
The second trial, the Veterans Affairs Diabetes Trial or VADT, found no increased risk of deaths, but no overall benefit from aggressive treatment.
New analyses of the data presented last week provide some insight into the differing findings but fail to answer the question of why some researchers saw increased risks while others didn't.
Two important conclusions they did reach, however, were that diabetics should avoid hypoglycemic episodes no matter what regimen is followed, and that aggressive treatment should begin as soon as possible after diagnosis.
The ACCORD trial enrolled 10,251 diabetics at 77 U.S. and Canadian clinics. Half received treatment to reduce A1c to between 7% and 7.9%, and half received aggressive treatment to try to reduce it to 6%.
Contrary to their initial speculation, the research team has now concluded that the excess deaths in the aggressive treatment arm were not caused by episodes of hypoglycemia, Dr. Matthew Riddle of the Oregon Health Science University in Portland told the meeting. Though severe hypoglycemia was associated with deaths, the risks were the same in both treatment groups.
The team did find a 20% increased risk of death for every 1% rise in A1c above 6%, Riddle said, "suggesting that lower blood glucose levels may be a worthy target." They also found that patients who were more easily able to reduce their A1c levels below 7% had a lower risk of death than those who struggled to do so.
And what caused the increased risk of death in the aggressive treatment group? "We don't know," Riddle said.
The VADT trial enrolled 1,791 patients from 20 VA medical centers, and had the same goals as ACCORD.
