NEW YORK - People with type 2 diabetes are 15 percent more likely to die from any cause and 14 percent more likely to die from a cardiovascular cause than non-diabetics at any given time, according to data from several Swedish registries.
The rates are significantly lower than previous estimates. Fifteen years ago, research was suggesting that having diabetes doubled the risk of premature death.
But the new study also found that the risk was dramatically elevated among people whose type 2 diabetes appeared by age 54. The worse their glycemic control and the more evidence of renal problems, the higher the risk.
In contrast, by age 75, type 2 diabetes posed little additional risk for people with good control and no kidney issues, according to the results.
"The overall increased risk of 15 percent among type 2 diabetics in general is a very low figure that has not been found in earlier type 2 diabetes studies," coauthor Dr. Marcus Lind of Uddevalla Hospital said in a telephone interview.
"The other thing that was interesting is that when we looked at patients with good glycemic control and no renal complications, if they were 75 years age, they had a lower risk than those in the general population. That hasn't been shown before," he said.
"What we are seeing is, if you are younger, aggressive management makes a difference," said Dr. Robert Ratner, chief scientific and medical officer of the American Diabetes Association, who was not involved in the research. At age 75, "you don't have to worry about it as much."
The study, published in the October 29 New England Journal of Medicine, is the largest to date to look at premature death in general - and death from cardiovascular causes in particular - among people with type 2 diabetes.
It compared more than 435,000 diabetics who were followed for a mean of 4.6 years with more than 2 million matched controls who were tracked for a mean of 4.8 years. The diabetics had had glucose problems for an average of 5.7 years.
In terms of actual death rates, cardiovascular mortality during the study period was 7.9 percent for diabetics versus 6.1 percent for controls (adjusted hazard ratio, 1.14; 95 percent confidence interval: 1.13-1.15). The respective rates for death from any cause were 17.7 percent and 14.5 percent (aHR, 1.15; 95 percent CI: 1.14-1.16).
For patients under age 55 with glycated hemoglobin levels below 7.0 percent, the risk of death from any cause nearly doubled (aHR, 1.92; 95 percent CI: 1.75-2.11).
"Those who are younger than 55, those who have target glycemic control and no signs of any renal complications, they had a clearly-elevated risk," said Dr. Lind.
But for people over 75, the hazard was actually 5 percent lower than it was for people without diabetes (aHR, 0.95; 95 percent CI: 0.94-0.96).
When the research team factored in people with normoalbuminuria, the risks were slightly mitigated.
Heart attack was the most common cause of death among diabetics.
When glycated hemoglobin levels were at 9.7 percent and higher for people below age 55, the hazard of death from any cause more than quadrupled. The hazard of death from cardiovascular causes rose more than five-fold.
Once again, the danger was far less extreme for people over 75, the researchers found.
"Excess mortality in type 2 diabetes was substantially higher with worsening glycemic control, severe renal complications, impaired renal function, and younger age," they concluded.
Renal function is a key element, Dr. Ratner said.
The study "reinforces the importance of early aggressive management of diabetes in order to prevent premature death and the fact is that the prevention of renal disease is probably the most potent thing we can do to reduce cardiovascular events," he said.
Dr. Lind said the risk may appear lower in the elderly because older people with diabetes are more likely to be getting aggressive treatment for their high blood pressure and high lipid levels, therapy that other people who also have hypertension and high cholesterol levels might not be receiving.
"I think that's the reason the rates are a bit lower" for seniors, he said.
Dr. Ratner said he believes the data for older diabetics simply reflects the fact that "you're seeing the survival cohort. They've made it past the difficult time."
We're all going to die, he said. "The issue is when does it happen? With diabetes, it's happening years ahead of time - in their 50s and early 60s, more so than when they reach 75. The younger you are, the greater that risk. That's when aggressive therapy should be given."