Diet as a risk factor for abnormal glucose tolerance in subjects with and without family history of diabetes mellitus

The relationship between diet and glucose tolerance was examined in 118 middle-aged subjects with normal glucose tolerance, impaired glucose tolerance and Type II diabetes mellitus. A significant relationship between body mass index and intake of protein and fat from animal source was observed in the whole study population and in subjects without family history of diabetes, but not in individuals with family history of the disease. An association between worsening of glucose tolerance and higher caloric intake was shown in males, but this appeared to be linked to the increased intake of animal fat and animal protein of these subjects. Adjusting for obesity and total intake of energy, no significant difference in intake of nutrients was detected in males, while in females a lower intake of refined carbohydrate, fibre and potassium was observed in diabetic subjects after adjustment for body mass index. In males without family history of diabetes, after adjustment for obesity and total energy intake a significant association between abnormal glucose tolerance and lower intake of plant protein as well as higher intake of protein from animal source was detected, while total and complex carbohydrate intake was lower in subjects with impaired glucose tolerance than in the two other diagnostic groups. In females without heredity of diabetes, a significantly lower intake of energy, carbohydrates, fibre, plant protein, calcium and potassium was detected in the diabetic group after adjustment for obesity. No significant difference in nutrient intake was observed in subjects with family history of diabetes. Even if evaluation of results is hampered by the limited number of subjects examined, findings of the study support in middle aged subjects an association between vegetarian diet and normal glucose tolerance, suggesting that this relationship might be enhanced in individuals without family history of diabetes