Regular consumption of yoghurt reduced the risk of developing Type 2 diabetes by 28%, scientists found.
Other low-fat fermented dairy foods, such as fromage frais and cottage cheese, also showed a health benefit, according to the study of more than 4,000 people.
Taken together, they reduced the chances of becoming diabetic by 24% over an 11-year period.
"This research highlights that specific foods may have an important role in the prevention of Type 2 diabetes and are relevant for public health messages," said lead scientist Dr Nita Forouhi, from the Medical Research Council (MRC) Epidemiology Unit at Cambridge University.
"At a time when we have a lot of other evidence that consuming high amounts of certain foods, such as added sugars and sugary drinks, is bad for our health, it is very reassuring to have messages about other foods like yoghurt and low-fat fermented dairy products, that could be good for our health."
While dairy products are important sources of protein, vitamins and minerals, they also contain saturated fat which can raise cholesterol levels and damage the heart and arteries.
However the association between dairy consumption and Type 2 diabetes has been unclear after inconclusive results from previous studies.
The new research involved participants in the large Epic-Norfolk study looking at links between diet and cancer in more than 25,000 men and women living in Norfolk.
Researchers compiled a detailed daily record of all the food and drink consumed in the course of a week by 4,255 participants, including 753 who developed Type 2 diabetes over 11 years.
Consumption of total dairy, high-fat dairy and low-fat dairy foods was not associated with new cases of diabetes once factors such as healthier lifestyles, education, obesity, other eating habits and calorie intake were accounted for.
But people with the highest consumption of low-fat fermented products were more than a fifth less likely to develop diabetes than non-consumers.
Yoghurt made up more than 85% of the fermented dairy products studied. When examined separately, it was associated with a 28% reduced risk of Type 2 diabetes.
The effect was seen in individuals who consumed an average of four-and-a-half standard 125 gram pots of yoghurt per week.
Consuming yoghurt in place of a snacks such as crisps was also found to reduce diabetes risk.
The findings appear in the latest edition of the journal Diabetologia, published by the European Association for the Study of Diabetes.
Beneficial probiotic bacteria and a special form of vitamin K in fermented dairy products may help to explain the results, say the scientists.
Type 2 diabetes, which causes blood sugar to rise, affects more than two million people in the UK and is linked to older age, genetic factors and obesity.
Dr Alasdair Rankin, director of research at the charity Diabetes UK, said: "This is a well-conducted research study, but linking specific components of our diet to the development of Type 2 diabetes is difficult and complicated, so we always need to be careful about the conclusions we draw.
"What it does suggest is that people in this study who included low-fat fermented dairy products such as yoghurt in their diet were less likely to develop Type 2 diabetes, and that yoghurt was one component of a healthy diet that reduced their risk alongside other healthy behaviours.
"So this study adds to evidence suggesting that the best way to reduce your risk of Type 2 diabetes is by maintaining a healthy lifestyle that includes plenty of physical activity and a balanced diet that is low in saturated fat, salt and sugar and rich in fruit and vegetables."