Attenuation of Postmeal Metabolic Indices with Red Raspberries in Individuals at Risk for Diabetes: A Randomized Controlled Trial

Obesity (Silver Spring). 2019 Apr;27(4):542-550. doi: 10.1002/oby.22406. Epub 2019 Feb 14.


Objective: This study investigated the effect of red raspberry intake on meal-induced postprandial metabolic responses in individuals who have overweight or obesity with prediabetes and insulin resistance (PreDM-IR), and in metabolically healthy individuals (Reference).

Methods: Thirty-two adults (PreDM-IR, n = 21; Reference, n = 11) were randomized to a controlled, three-arm, single-blinded, crossover trial. Participants were provided 0 g of frozen red raspberries (Control), 125 g of frozen red raspberries (RR-125) (~1 cup), or 250 g of frozen red raspberries (RR-250) (~2 cups), with a challenge breakfast meal (high carbohydrate/moderate fat) on three separate days. Multiple blood samples were collected up to 8 hours post breakfast with a final blood sample at 24 hours. A snack was provided at 6 hours.

Results: Breakfast containing RR-125 and RR-250 significantly reduced 2-hour insulin area under the curve, and RR-250 reduced peak insulin, peak glucose, and 2-hour glucose AUC compared with Control in the PreDM-IR group (P < 0.05). Postprandial triglycerides were significantly lower after RR-125 versus RR-250 (P = 0.01) but not different from Control (P > 0.05). No significant meal-related differences were observed for oxidative stress or inflammatory biomarkers.

Conclusions: Our findings suggest that red raspberries aid in postmeal glycemic control in individuals with PreDM-IR, reducing glycemic burden with less insulin, which may be related to improved tissue insulin sensitivity.

Trial registration: NCT02479035.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Biomarkers / blood
  • Blood Glucose / metabolism
  • Breakfast
  • Cross-Over Studies
  • Diabetes Mellitus, Type 2 / metabolism
  • Diabetes Mellitus, Type 2 / prevention & control*
  • Female
  • Fruit*
  • Health Status Indicators
  • Humans
  • Insulin / blood
  • Insulin Resistance
  • Male
  • Middle Aged
  • Obesity / blood
  • Obesity / diet therapy
  • Obesity / metabolism
  • Overweight / blood
  • Overweight / diet therapy
  • Overweight / metabolism
  • Postprandial Period / physiology
  • Prediabetic State / diet therapy*
  • Prediabetic State / metabolism*
  • Risk Factors
  • Rubus* / physiology
  • Triglycerides / blood


  • Biomarkers
  • Blood Glucose
  • Insulin
  • Triglycerides

Associated data