By Gene Emery

(Reuters Health) – Weight gain can be a big concern for smokers who want to quit, and a new study suggests that it raises the odds of developing type 2 diabetes in the first six years after quitting.

But any new health risks gained by putting on a few extra pounds are overwhelmed by the health benefits of giving up tobacco, researchers report in The New England Journal of Medicine.

The analysis found that weight gains up to 5 kg (11.02 lb) after quitting raised the risk of developing diabetes by about 15 percent compared to continuing smokers, and greater weight gains increased the risk proportionately. But that risk began declining after five to seven years to eventually match that of never-smokers.

“The more weight you gain, the more the risk. But the risk of developing diabetes is short term,” senior study author Dr. Qi Sun of the Harvard T.H. Chan School of Public Health in Boston told Reuters Health in a telephone interview.

“Even more importantly, regardless of how much weight quitters gain, they really have a reduced risk of dying from cardiovascular disease. This is very important for smokers to know,” he said. “And if they minimize their weight gain, they can maximize their benefits.”

“The cardiovascular and overall mortality benefits of stopping smoking far outweigh the risks of acquiring type 2 diabetes,” Dr. Steven Schroeder of the University of California, San Francisco agreed in a journal editorial.

While a weight gain of 5.1 kg (11.24 lb) to 10 kg (22.05 lb) by recent quitters increased the odds of developing blood sugar problems by 36 percent, for example, quitting smoking cut their odds of death from heart attack, stroke and other cardiovascular disease by 75 percent. Their odds of death from any cause were also 54 percent lower compared with continuing smokers.

Even a weight gain of more than 10 kg favored quitting. The risk of diabetes rose 59 percent but the likelihood of death from heart and stroke problems declined by 67 percent and the overall death rate was cut by 50 percent.

With no weight gain, quitters’ diabetes risk did not increase, but their death rate from cardiovascular disease dropped by 53 percent and the odds of death from any cause by 48 percent.

Smoking itself was also linked to increased risk of type 2 diabetes. People who had never smoked were 28 percent less likely to develop blood sugar problems, the researchers found.

The study used health records from three large databases of mostly-white doctors and nurses, with data going back to 1984.

Ultimately, the cases of 162,807 people were used to assess diabetes risk and 170,723 were used to gauge mortality. Body weight was logged over the first six years after quitting.

“It should be acknowledged,” Schroeder writes in his editorial, “that the participants in the three cohorts, all health professionals, had health risks and behaviors that did not mirror those of smokers in 2018, who tend to be concentrated among vulnerable populations” such as minorities.

Thirty years after quitting, the odds of developing type 2 diabetes were the same for former smokers as for people who had never smoked.

“In our analyses, we estimated that weight change within 6 years after quitting explained 68.4 percent of the increased risk of type 2 diabetes,” the researchers write. “Preventing excessive weight gain may maximize the health benefits of smoking cessation through reducing the short-term risk of diabetes and further lowering the long-term risk of death.”

About 16 percent of adults in the U.S., or nearly 38 million, smoke cigarettes, according to the Centers for Disease Control and Prevention.

SOURCE: The New England Journal of Medicine, online August 15, 2018.