New research debuted at the American Diabetes Association's 72nd Annual Scientific Session suggests eating raisins three times a day may significantly lower postprandial (post-meal) glucose levels when compared to common alternative snacks of equal caloric value. The study was conducted at the Louisville Metabolic and Atherosclerosis Center (L-MARC) by lead researcher, Harold Bays, MD, medical director and president of L-MARC.

The study was conducted among 46 men and women who had not previously been diagnosed with diabetes mellitus, but who had mild elevations in glucose levels. Participants were randomly assigned to snack on raisins or pre-packaged commercial snacks that did not contain raisins or other fruits or vegetables, three times a day for 12 weeks. Findings included:
  • Compared to control snacks, raisins significantly decreased mean post-meal glucose levels by 16 percent
  • Compared to baseline within group paired analysis, raisins significantly reduced mean hemoglobin A1c by 0.12 percent
  • Consumption of the control snacks in the study did not significantly reduce mean post-meal glucose or hemoglobin A1c
"Compared to the snacking control group, the group consuming raisins had a significant statistical reduction in their after-liquid meal blood sugar levels among study participants who had mean baseline fasting glucose levels between 90 and 100 mg/dl.," said Dr. Bays. "This favorable glucose effect of raisins was further supported by the statistically significant reduction in hemoglobin A1c (a standard test for overall blood sugar control in diabetes mellitus) in the within group comparison to baseline. The within group comparisons from baseline with snacks did not demonstrate a reduction in hemoglobin A1c."

The study was funded by the California Raisin Marketing Board through a grant to the L-MARC Research Center in Louisville, Kentucky.

"Raisins have a relatively low glycemic index and contain fiber and antioxidants, all factors which contribute to blood sugar control," said James Painter, Ph.D., R.D., and nutrition research advisor for the California Raisin Marketing Board. "Decreasing blood sugar and maintaining normal hemoglobin A1c levels is important because it can prevent long-term damage to the heart and circulatory system."

This research is part of a two-part study by L-MARC that looked at raisins and possible impacts to blood pressure and blood sugar levels. The first part of the study announced at the American College of Cardiology's 61st Annual Scientific Session suggests eating raisins three times a day may significantly lower blood pressure among individuals with slightly higher than normal blood pressure, otherwise known as prehypertension.