An increase in dietary protein improves the blood glucose response in persons with type 2 diabetes

Mary C Gannon, frank q Nuttall, Asad Saeed, Kelly Jordan, Heidi Hoover

Research output: Contribution to journalArticlepeer-review

297 Scopus citations


Background: In single-meal studies, dietary protein does not result in an increase in glucose concentrations in persons with or without type 2 diabetes, even though the resulting amino acids can be used for gluconeogenesis. Objective: The metabolic effects of a high-protein diet were compared with those of the prototypical healthy (control) diet, which is currently recommended by several scientific organizations. Design: The metabolic effects of both diets, consumed for 5 wk each (separated by a 2-5-wk washout period), were studied in 12 subjects with untreated type 2 diabetes. The ratio of protein to carbohydrate to fat was 30:40:30 in the high-protein diet and 15:55:30 in the control diet. The subjects remained weight-stable during the study. Results: With the fasting glucose concentration used as a baseline from which to determine the area under the curve, the high-protein diet resulted in a 40% decrease in the mean 24-h integrated glucose area response. Glycated hemoglobin decreased 0.8% and 0.3% after 5 wk of the high-protein and control diets, respectively; the difference was significant (P < 0.05). The rate of change over time was also significantly greater after the high-protein diet than after the control diet (P < 0.001). Fasting triacylglycerol was significantly lower after the high-protein diet than after the control diet. Insulin, C-peptide, and free fatty acid concentrations were not significantly different after the 2 diets. Conclusion: A high-protein diet lowers blood glucose postprandially in persons with type 2 diabetes and improves overall glucose control. However, longer-term studies are necessary to determine the total magnitude of response, possible adverse effects, and the long-term acceptability of the diet.

Original languageEnglish (US)
Pages (from-to)734-741
Number of pages8
JournalAmerican Journal of Clinical Nutrition
Issue number4
StatePublished - Oct 2003


  • Diabetes
  • Diet
  • Dietary protein
  • Glucagon
  • Glycated hemoglobin
  • Glycemic index
  • Insulin
  • Triacylglycerol


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