A new study reports that weight, diet, exercise, smoking and alcohol intake may each independently influence a person's risk of getting diabetes.
Researchers found that even when people had a family history of diabetes or were overweight, they were less likely to get the chronic disease if they were healthy in other ways.
And each additional lifestyle improvement lowered their risk.
"There are implications certainly for individuals to take one step at a time towards a healthy lifestyle," said Jared Reis, one of the study's authors from the National Heart, Lung, and Blood Institute in Bethesda, Maryland.
Benefits of a healthy lifestyle
And, he told Reuters Health, there is certainly benefit for those who may have a tough time with losing weight if they adopt these other healthy lifestyle factors.
The data came from more than 200,000 Americans who filled out surveys about their lifestyle, diet and health status in 1995 and 1996, when most were in their fifties and sixties. None of them had diabetes at the start of the study.
Ten years later, researchers sent them another survey asking whether they had been diagnosed with diabetes.
In all, about one in 10 men and one in 13 women reported having the disease.
Healthy diet lowers risk
Looking back at the original surveys, the researchers broke health and lifestyle-related questions into five categories: body mass index (BMI, a measure of weight in relation to height), diet, physical activity, smoking and alcohol consumption.
They found that each healthy behaviour listed on that survey – such as exercising for at least 20 minutes a day, three times per week, or never smoking or quitting at least a decade ago – lowered a person's future diabetes risk independent of the other lifestyle components.
For example, people who smoked, drank heavily, and got little exercise still had a lower diabetes risk if they ate a healthy diet than if they ate lots of saturated fats and few fibre-rich whole grains.
That was also the case for people who had a family history of diabetes, and so were at higher risk to begin with.
Weight a factor in diabetes risk
Overall, normal-weight women who ate a healthy diet, exercised, drank moderately and didn't smoke were 8 % less likely to get diabetes than women who were overweight and didn't fit any of the criteria for a healthy lifestyle. For healthy men, the diabetes risk was cut by 72% compared to men with unhealthy habits.
Even though heavy people were still better off if they were healthy in other ways, the researchers said weight was the most important factor in predicting who developed diabetes.
"While the message is that all these things matter... the number one top-of-the-list take-home is, don't be overweight in the first place," said Dr Lawrence Phillips, an endocrinologist at Emory University in Atlanta who wasn't involved in the new research. "It's important not to confuse the baby with the bathwater here," he added.
Asians more at risk
Lawrence also pointed out that the cut-off used to define a normal, healthy weight in the study was a BMI of 25 – the equivalent of someone who is five feet, five inches and weighs 150Kgs.
While that's realistic for people who are white, he told Reuters Health, studies have suggested that Asians and people of other ethnicities might have an increased diabetes risk at lower BMIs as well, and that their threshold for being overweight may be different.
One limitation to the study, the researchers reported in Annals of Internal Medicine, is that participants may have changed their lifestyle during the decade following the first survey – and those changes wouldn't be reflected in the findings.
Cutting fats no guarantee
The study also can't prove definitively that by cutting out cigarettes or saturated fats, any one person can lower his or her risk of diabetes. It's possible, for example, that people who exercised less were also less healthy for other reasons not measured by the surveys.
But Dr David Jenkins, a nutrition researcher from the University of Toronto who also didn't participate in the new study, said the findings point to a way forward for people who are motivated to lower their risk of diabetes. "This just says, look, this is what you have to do," he told Reuters Health.
"This would suggest again that even for those who have a family history, if you adopt a healthy lifestyle you can have a strong influence on whether you end up developing diabetes," Reis said.
"The fact that those findings are evident in this older population is also a good thing," he said. "It means it's never too late."
(Reuters Health, September 2011)