PhD Candidate Montana State University Bozeman, Montana
Define insulin sensitivity and compare how long-term intake of varying weekly doses of lentils impact insulin sensitivity.
Lentils, a type of pulse crop, promote a lower blood glucose and insulin response than observed with ingestion of high glycemic index foods. However, long-term lentil consumption in humans has not been evaluated for its ability to improve glycemic control. The purpose of this study was to determine the effects of different doses of lentils for 8-weeks on whole body insulin resistance and sensitivity.
In this randomized controlled trial, non-diabetic overweight and obese adults (n=30) with increased waist circumference underwent a 75g oral glucose tolerance test (OGTT) with white bread before and after an 8-week dietary intervention. The diet included 5 prepared mid-day meals each week that were isocaloric but varied in dose of green lentils per week: 0 cups (CON), 1.5 cups (MOD), and 3 cups (HI). Blood glucose and insulin were used to calculate insulin resistance and sensitivity (HOMA-IR & Matsuda Index) and glycemic responses (iAUC). The impact of the diet on insulin sensitivity controlling for age and BMI was analyzed with linear models.
Only MOD improved insulin iAUC to OGTT, with an 8.6% decrease from CON (p=0.03). Glucose iAUC did not improve for any group after 8 weeks (p=0.22). In HI, HOMA-IR was 37.3% less than CON (p<0.01). Matsuda Index was 24.4% (p=0.06) and 26.7% (p=0.05) higher respectively in MOD and HI compared to CON.
These data suggest that long-term addition of lentils can improve insulin responses and sensitivity in heavier individuals at greater risk of impaired glucose tolerance.