TUESDAY, Sept. 27 (HealthDay News) -- For people with type 2 diabetes, intense treatment doesn't slow decline in thinking skills, a new study found. Super-strict blood sugar control actually appeared to increase study participants' risk of death, the researchers found.

People older than 70 with type 2 diabetes are twice as likely to suffer mental impairment as those without diabetes, researchers say. Intensively controlling blood sugar has been shown to reduce the odds of diabetes complications, such as vision, kidney and circulation problems, so it seemed likely that it might also slow any cognitive decline related to the condition.

"At the end of the day, there was no difference in cognitive function between people who received the intensive strategy versus the standard strategy," said lead researcher Lenore J. Launer, at the Laboratory of Epidemiology, Demography and Biometry at the U.S. National Institute on Aging.

Launer said they went into the study assuming intensive lowering of blood sugar would improve cognitive function. Since there were no non-diabetics in the study for comparison purposes, it is still possible that routine control of blood sugar does confer a benefit on cognitive function, she said.

"Patients should follow standard therapy, because there is no additional benefit to following a more intensive strategy," she advised.

It is important for people with type 2 diabetes to keep their blood sugar under control to reduce the likelihood of long-term complications. While the study didn't confirm cognitive advantages, many other health benefits are associated with well-controlled blood sugar, Launer said.

The study was published in the Sept. 27 online edition of The Lancet Neurology.

Launer's group looked at a subset of patients who took part in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial.

Researchers assigned 2,977 with type 2 diabetes at high risk for heart disease to intensive blood-sugar lowering or current treatment. The participants were 55 to 80 years old. Intensive blood sugar lowering meant reducing blood sugar to less than 6 percent as measured by an A1c test. The current standard is to maintain blood sugar at between 7 and 7.5 percent.

Some patients (614) also had an MRI to measure brain volume and took cognitive ability tests at the beginning and end of the study.

After about 39 months, no difference in cognitive ability existed between the groups, the researchers found. However, patients in the intensive care group had a significantly larger brain volume than patients in the standard treatment group.

But, the larger brain volume didn't translate to better thinking abilities.

The part of the ACCORD trial involving intensive lowering of blood sugar was halted earlier than planned. An increased risk of death, the finding of no overall benefit on cardiovascular disease, problems caused by too-low blood sugar and weight gain were all factors in stopping.

Dr. Geert Jan Biessels, a neurologist at the Rudolf Magnus Institute of Neuroscience at the University Medical Center in Utrecht, the Netherlands, wrote a journal editorial accompanying the study. He said that "dementia is the most important cognitive complication of diabetes. The present study assessed the effects of treatment on average cognitive functioning across the whole study population. It is uncertain, however, if average cognitive functioning is an adequate proxy for dementia."

On average, cognition was not improved, he said. "However, the absence of an effect of treatment on mean cognitive functioning cannot yet be regarded as proof that the treatment may not delay dementia," he said. "But, at present the results do not support specific treatments to prevent cognitive decline in diabetes."

Another expert, Dr. Jay Skyler, a professor of medicine at the Diabetes Research Institute of the University of Miami Miller School of Medicine, said that "the study does not answer the question as to whether among diabetics cognitive dysfunction might be more accelerated than in the general population and whether treatment might control that."

More information

For more information on diabetes, visit the U.S. National Library of Medicine.