What is the relationship between the intake of cooked dry beans and peas and type 2 diabetes?

Limited evidence is available to determine a relationship between the intake of cooked dry beans and peas and type 2 diabetes.

Only one study was found that measured the relationship between dry beans and peas and type 2 diabetes (T2D). The association between the consumption of legume and soy foods and T2D was examined over an average follow-up of approximately five years in the Shanghai Women’s Health Study (Villegas, 2005). Average daily intake of individual food items was combined for the following food groups: Total legumes and three mutually exclusive groups [soybeans (dried and fresh), peanuts and other legumes]. The median intake of total legumes was 30.5g per day, for soybeans was 11.0g per day, for peanuts was 0.7g per day, and for other legumes was 15.5g per day. Total legume consumption and consumption of soybeans and other legumes were each associated with a decrease in risk of T2D.

Villegas et al, 2005 (positive quality), a prospective cohort study (Shanghai Women’s Health Study) conducted in China, examined the association between legume and soy food consumption and self-reported T2D. Participants were 64,191 women aged 40-70 years. Dietary intake was assessed by validated food-frequency questionnaire (FFQ). Mean follow-up was 4.6 years. Average daily intake of individual food items (grams per day) was combined to compute the following food groups: Total legumes and three mutually exclusive groups [soybeans (dried and fresh), peanuts and other legumes]; soy milk and “other soy products” were analyzed separately. The median intake of total legumes was 30.5g per day, for soybeans was 11.0g per day, for peanuts was 0.7g per day and for other legumes was 15.5g per day. Total legume consumption and consumption of soybeans and other legumes were each associated with a decrease in risk of T2D:

• All legumes relative risk (RR) between extreme quintiles=0.62; 95% CI: 0.51, 0.74; P for trend<0.0001
• Soybeans RR between extreme quintiles=0.53; 95% CI: 0.45, 0.62; P for trend<0.0001
• Other legumes (not including peanuts) RR between extreme quintiles=0.76; 95% CI: 0.64, 0.90; P for trend<0.0001
• Soy milk RR between high and no intake=0.61; 95% CI: 0.54, 0.70; P for trend<0.0001.

There was no significant (NS) association between consumption of other soy products or total soy protein and the risk of T2D. The authors concluded that consumption of legumes was inversely associated with the risk of T2D in this population.