Diabetics who tightly control their blood sugar - even if only for the first decade after they are diagnosed - have lower risks of heart attack, death and other complications 10 or more years later, a large follow-up study has found.
The discovery of this "legacy effect" may put new emphasis on rigorous treatment when people first learn they have Type 2 diabetes, the most common form and the type linked to obesity.
Doctors warn that people should not let their blood sugar spin out of control - that could have serious health consequences.
"What you don't want is for people to think that they had a period of good glucose control and then they allow their blood glucose to go high - that would be disadvantageous," said Dr. Stephen Davis, head of Vanderbilt University's diabetes and endocrinology division, who had no role in the study.
Results were published online Wednesday by the New England Journal of Medicine and were being presented at the European Association for the Study of Diabetes meeting in Rome.
Diabetes affects more than 18 million Americans. Most have Type 2, which occurs when the body makes too little insulin or cannot use what it does produce. Being overweight raises this risk.
Researchers led by Dr. Rury Holman at the University of Oxford in England originally studied 4,209 newly diagnosed diabetes patients assigned to manage their blood sugar either through standard diet restrictions or medicines. In the drug group, most took sulfonylurea, which prompts the pancreas to release more natural insulin into the bloodstream. Overweight diabetics took metformin, sold in the United States as Glucophage. Treatment lasted on average 10 years.
That study showed intensive blood sugar control lowered the risks of eye disease and kidney damage, but did not find any significant difference in heart attack risk except in the overweight group taking metformin. Those results led to guidelines recommending tight blood sugar control still in wide use today.
The follow-up study was on 3,277 participants who were tracked for an average of 10 more years - first in clinics, where blood sugar could be measured, and through questionnaires in the later years.
Within one year of the original study ending, differences in blood sugar control between the groups disappeared.
Despite that, the sulfonylurea group had a 15 per cent lower risk of heart attack and a 13 per cent lower risk of death compared with the diet group.
The benefits were even greater among overweight diabetics on metformin, who had a 33 per cent lower risk of heart attack and a 27 per cent reduced risk of death.
"It really stresses the importance of taking the long term-view of a chronic disease," said Dr. Judith Fradkin, who heads the diabetes division at the National Institute of Diabetes and Digestive and Kidney Diseases.
"This really gives information on steps that people can take that's going to improve their health," said Fradkin, who had no role in the latest research.
In a related study, Oxford researchers failed to find the same benefit among nearly 1,000 diabetics who maintained strict control of their blood pressure early on and then lapsed. There was no significant reduction in stroke, death or diabetes-related complications among those who initially had tight blood pressure control compared with those who did not.
Both studies were funded by various British government health organizations and advocacy groups. Six major drug companies, including the makers of diabetes drugs, also supported the research.
Dr. Alvin C. Powers, director of Vanderbilt's diabetes centre, said the studies underscore the need to treat diabetes in a holistic manner - managing blood sugar, blood pressure and cholesterol levels.
"The important message is that it re-emphasizes that glucose control is important," said Powers, who is not connected with the research.
Recent attention on the impact of tight blood sugar rose after the U.S. government stopped a diabetes trial earlier this year after a surprising number of deaths among patients who pushed down their blood sugar. However, that study was done in high-risk patients who had taken diabetes medications for many years - not newly diagnosed patients.
