Tracking 41,000 men for twelve years, scientists at the Massachusetts General Hospital (MGH), Harvard School of Public Health (HSPH) and Brigham and Women's Hospital (BWH) found that men who ate higher levels of dairy products, especially low-fat dairy foods, had a significantly lower risk of developing type 2 diabetes.
The numbers of consumers with diabetes are rising the world over, linked to lifestyle factors such as diet, exercise and weight, all established risk factors for type 2 diabetes.
An estimated 41 million Americans have 'pre-diabetes', or impaired glucose tolerance, in which blood sugar levels are higher than normal and lead to high risk of developing type 2 diabetes.
And around 25 per cent of UK adults are also believed to have this condition: the number of people with diabetes, now 3 per cent of the population, will continue to rise as the population ages and becomes increasingly overweight.
"While individuals should consider both the benefits and risks of dairy foods before considering changing their diets, consuming up to two servings daily of low-fat dairy products can probably be recommended for most people," says Hyon Choi, the paper's lead author.
The mechanism behind the dairy intake and diabetes risk needs to be clarified, adds the author, who has proposed further studies should investigate whether adjusting dairy intake could be helpful to people with already established type 2 diabetes.
Initiated in 1986, the Health Professionals Follow-up study in the US has gathered information regarding the relationship between dietary factors and several illnesses from more than 50,000 men employed in the health professions.
Every two years participants complete questionnaires regarding their diseases and health-related topics like smoking and exercise, and every four years the questionnaires also collect comprehensive dietary information.
The current study evaluated information from more than 41,000 participants who did not have diabetes, cardiovascular disease or cancer when the study began.
Those men who reported developing type 2 diabetes during the study period completed a supplementary survey, which confirmed the diagnosis in about 1,200 participants. The researchers then analysed the dietary information all participants provided in 1986, 1990 and 1994 to determine how diet related to their risk of developing diabetes.
Results showed that those men consuming higher levels of dairy foods had significantly less risk of developing type 2 diabetes than those who consumed the lowest levels.
A further analysis showed the risk reduction was almost exclusively associated with low-fat or non-fat dairy foods.
In general, each serving-per-day increase in dairy intake resulted in a 9 per cent reduction in the risk of developing the disorder.
Controlling for consumption of several other types of food, activity level and family history did not change the association.
"Additional studies will be required both to confirm this relationship and to see if the results apply to women or to men younger than this group, who were in their 50s when they joined the study," says Choi.
Full findings are published in the 9 May issue of Archives of Internal Medicine, one of the JAMA/Archives journals.