Intensive treatment of blood glucose levels may be more beneficial in those younger than 60. (CBC)

Aggressively treating some people with Type 2 diabetes to lower their blood sugar levels may increase the risk of premature death, researchers have found.

If the findings are confirmed, then the team suggested revising diabetes guidelines to include a minimum blood sugar in addition to current maximum levels.

Doctors generally aim to keep blood sugar levels low and as close to normal as possible to minimize complications such as heart attacks, strokes, kidney problems, amputations and blindness.

The study, published in Wednesday's online issue of the The Lancet, used data on patients aged 50 or older in the U.K. from November 1986 to November 2008.

Of those studied, 27,965 had their treatment increased from one drug to a combination of two drugs aimed at lowering blood sugar levels, and another 20,005 had their regimen changed to include insulin.

Mortality from low, high blood sugar

Blood glucose levels were based on HbA1c levels — the proportion of red blood cells with glucose attached to them. The HbA1c level with the lowest mortality risk, 7.5 per cent, was used as a reference point or control.

Risk of death among those with the lowest blood sugar levels (average HbA1c of 6.4 per cent) was 1.52 times higher than the reference group.

Those with the highest blood sugar levels over time (average HbA1c of 10.5 per cent) had a risk of death 1.79 times higher than the reference group.

The death risk in people given insulin-based treatment was 1.49 times higher than those given oral medicines.

During the study, there were 2,834 deaths among those given insulin-based regimens compared with 2,035 among those taking pills.

"Low and high mean HbA1c values were associated with increased all-cause mortality and cardiac events. If confirmed, diabetes guidelines might need revision to include a minimum HbA1c value," Dr. Craig Currie of the school of medicine at Cardiff University in Wales and his co-authors concluded.

The researchers cautioned against stopping efforts to lower blood sugar through medication including insulin.

Patient-specific treatment

The actual causes of death were not included in the study, which was not a randomized control trial and cannot show a cause-and-effect relationship.

The higher risk of death was found among patients who were generally older and sicker.

The study had the advantage of dealing with observations in the real world, Dr. Beverley Balkau and Dr. Dominique Simon of the CESP Centre for Research in Epidemiology and Population Health in Villejuif, France, noted in a journal commentary that accompanies the research.

"Today's study does provide a rationale for an HbA1c threshold of 7.5 per cent," the pair wrote.

"More research is needed to establish HbA1c thresholds and the combination of drugs to be recommended for intensive treatment, with perhaps differing recommendations according to the patient — intensive treatment seems to be more beneficial for cardiovascular outcomes for those who are younger than 60 years, with a short duration of diabetes, and absence of" cardiovascular disease and other complications of diabetes.

The study is not the first to look at aggressive drug treatment to normalize blood sugar levels as much as possible.

In February 2009, the ACCORD trial sponsored by the U.S. government was stopped because there were 20 per cent more deaths among diabetics with heart problems who were treated intensively compared with those receiving conventional treatment.

The study was funded by Eli Lilly and Co.