This study examines the impact of daily consumption of ½ c pinto beans, compared to a control (½ c green beans), on fasting glucose, postprandial glucose and HbA1c concentrations in adults with type 2 diabetes mellitus (T2DM).

This study utilized a randomized, pretest-posttest, crossover (within-group) design, that includes two treatment periods [control period (½ c. green beans each day) and pinto beans (½ c each day)], each 12-weeks in duration with a 4- week wash-out period to determine the impact on fasting glucose, postprandial glucose and HbA1c concentrations. After a baseline wash-in period, 16 participants are randomly assigned to 2 treatment periods [control period and pinto beans], each 12-weeks in duration. On 28 randomized days during the wash-in period and interventions, participants keep diet records and measure a postprandial capillary glucose concentration using a glucometer 1 hour after the meal during which the pinto beans or control are consumed. Before and after each 12-week intervention, participants provide a fasted venous blood sample for glucose and HbA1c analyses.

Inclusion Criteria:

• diagnosis of T2DM by a physician;
• currently attempting control of T2DM by diet or metformin;
• fasting glucose ≥ 90 mg/dL (confirmed by fasting blood draw or potential participant provided lab analysis conducted within last 30 days) and/or hemoglobin A1C ≥ 6.5% (confirmed by blood draw or potential participant provided lab analysis conducted within last 30 days);
• body mass index (BMI) of 22-40 kg/m2;
• no unresolved health conditions and no diagnosis of gastrointestinal disease;
• limited history of legume intake;
• willingness to follow study protocol, scheduling, and ability to come to the testing location;
• no recent weight gain or loss (>10% over 6 months);
• no use of medications and/or dietary supplements other than metformin that affected glucose;
• women could not be pregnant or breastfeeding;
• habitual alcohol consumption had to be less than 2 drinks per day (specifically ≤ 720 ml of beer, 240 ml of wine, or 90 ml of hard liquor).

Exclusion Criteria:

• Non compliance with above inclusion criteria.