If someone is following a high slow-release carbohydrates diet for a long time (rice, oat, cereals, nuts, etc), will it increase the chance of developing diabetes in the future?
Are there studies supporting or denying this relation?
Diet high in whole-grains ("slow-release carbohydrates") was associated with a decreased risk of diabetes 2, according to 2 systematic reviews of studies:
Source 1 (PubMed)
Whole grain intake is inversely associated with risk of type 2 diabetes.
Source 2 (PubMed)
...consuming three servings of whole grain foods (45 g of whole grain ingredients) daily would induce a 20% relative reduction in the T2D risk as compared to consuming a half serving (7.5 g of whole grain ingredients).
In some studies, high intake of sugar was associated with diabetes type 2, but it is not clear if it is high sugar intake or high calorie intake that was actually associated with diabetes 2.
Source 3 (PubMed)
Higher consumption of sugar-sweetened beverages is associated with a greater magnitude of weight gain and an increased risk for development of type 2 diabetes in women, possibly by providing excessive calories and large amounts of rapidly absorbable sugars.
As shown here, a high carb, low fat diet is going to significantly reduce the chance of developing diabetes and cardiovascular disease provided you get your carbs from healthy sources like e.g. whole grains, brown rice etc. Now, there are many studies that show a clear benefit to eating a low carb diet for obese people, and people who have (pre)diabetes. But here the focus is on weight loss and improved blood sugar levels, which are not relevant health indicators for people who are healthy to begin with.
The basic point made in these more general and less rigorous arguments is that a natural diet for humans is a plat based diet, all the fats in our diets should then come from the plants we eat. Oils are refined calories with low nutritional value, they should be avoided. We are genetically adapted to live on such a diet where the calories from fats will be of the order of 10%.
If you then put this to the test, study populations who live on such a diet and consider the health of the population, the fraction of the population who are obese, suffer from diabetes, heart disease etc. then what you find is that these levels are not a factor 2 lower, not a factor 10 lower, but typically more than a factor 100 lower. Take e.g. this study:
Shaper started with the observation as a clinician in the 1950s that coronary heart disease in the African population in Uganda was almost non-existent, and this appeared to be confirmed by necropsy studies. On the other hand, coronary heart disease appeared to be a major problem in the Asian community in Ugandawith a high proportion of deaths attributed to coronary heart disease.
Though Shaper and Jones did not appear to collect detailed dietary data from individuals in the study apart from identifying vegetarians and non-vegetarians in the Asian group, they presented descriptions of dietary patterns then prevalent in African and Asian communities around Kampala. They cited reports from other studies indicating relatively low meat and fat intakes (∼16–20 g a day) in the African communities, with possibly up to 40 g fat a day in more well-to-do families. With estimated intake of 2000 calories per day, this would be ∼10–20% of total caloric intake. In contrast, though Asian communities comprised Hindus who were largely lacto-ovo-vegetarians, and Muslims who had meat, fish and poultry in their diets, it was estimated that fat and oils provided a large proportion, ∼30–40%, of total caloric intake in the Asian community, whatever the religious or dietary group.
Such results have been replicated in many other studies. Only a few small scale intervention studies have been done. It's obviously extremely difficult to put people on a diet that's so extremely different from what they are used to eating.