A high-protein breakfast induces greater insulin and glucose-dependent insulinotropic peptide responses to a subsequent lunch meal in individuals with type 2 diabetes

Abstract

Background: The previous meal modulates the postprandial glycemic responses to a subsequent meal; this is termed the second-meal phenomenon.

Objective: This study examined the effects of high-protein vs. high-carbohydrate breakfast meals on the metabolic and incretin responses after the breakfast and lunch meals.

Methods: Twelve type 2 diabetic men and women [age: 21-55 y; body mass index (BMI): 30-40 kg/m(2)] completed two 7-d breakfast conditions consisting of 500-kcal breakfast meals as protein (35% protein/45% carbohydrate) or carbohydrate (15% protein/65% carbohydrate). On day 7, subjects completed an 8-h testing day. After an overnight fast, the subjects consumed their respective breakfast followed by a standard 500-kcal high-carbohydrate lunch meal 4 h later. Blood samples were taken throughout the day for assessment of 4-h postbreakfast and 4-h postlunch total area under the curve (AUC) for glucose, insulin, C-peptide, glucagon, glucose-dependent insulinotropic peptide (GIP), and glucagon-like peptide 1 (GLP-1).

Results: Postbreakfast glucose and GIP AUCs were lower after the protein (17%) vs. after the carbohydrate (23%) condition (P < 0.05), whereas postbreakfast insulin, C-peptide, glucagon, and GLP-1 AUCs were not different between conditions. A protein-rich breakfast may reduce the consequences of hyperglycemia in this population. Postlunch insulin, C-peptide, and GIP AUCs were greater after the protein condition vs. after the carbohydrate condition (second-meal phenomenon; all, P < 0.05), but postlunch AUCs were not different between conditions. The overall glucose, glucagon, and GLP-1 responses (e.g., 8 h) were greater after the protein condition vs. after the carbohydrate condition (all, P < 0.05).

Conclusions: In type 2 diabetic individuals, compared with a high-carbohydrate breakfast, the consumption of a high-protein breakfast meal attenuates the postprandial glucose response and does not magnify the response to the second meal. Insulin, C-peptide, and GIP concentrations demonstrate the second-meal phenomenon and most likely aid in keeping the glucose concentrations controlled in response to the subsequent meal. The trial was registered at www.clinicaltrials.gov/ct2/show/NCT02180646 as NCT02180646.

Keywords: GIP; GLP-1; glucagon; high carbohydrate; postprandial glucose; second-meal phenomenon; type 2 diabetes.

© 2015 American Society for Nutrition.

Figures

FIGURE 1

Glucose (A, B) and insulin (C, D) concentration (A, C) and AUC (B, D) responses to either a high-protein or a high-carbohydrate breakfast and a standardized lunch in individuals with T2D. Subjects were studied over an 8-h study day. Arrow indicates when meals were consumed. Values are means ± SEMs, n = 12. *Different between breakfast and lunch, P < 0.05; **Different from corresponding breakfast, P < 0.05; †Different from corresponding lunch, P < 0.05. CHO, carbohydrate breakfast; PRO, protein breakfast; T2D, type 2 diabetes.

FIGURE 2

C-peptide concentration (A) and AUC (B) and glucagon concentration (C) and AUC (D) responses to either a high-protein or a high-carbohydrate breakfast and a standardized lunch in individuals with T2D. Arrows indicate when meals were consumed. Values are means ± SEMs, n = 12. *Between breakfast and lunch,P < 0.05; **Different from corresponding lunch,P < 0.05; †Different by meal composition,P < 0.05. CHO, carbohydrate breakfast; PRO, protein breakfast; T2D, type 2 diabetes.

FIGURE 3

Hepatic insulin extraction AUC (A), FFA concentrations (B), insulin secretion (C), and glucagon/insulin ratio (D) responses to either a high-protein or a high-carbohydrate breakfast and a standardized lunch in individuals with T2D. Arrows indicate when meals were consumed. Values are means ± SEMs, n = 12. *Different between breakfast and lunch, P < 0.05. CHO, carbohydrate breakfast; PRO, protein breakfast; T2D, type 2 diabetes.

FIGURE 4

GIP concentration (A) and AUC (B) and GLP-1 concentration (C) and AUC (D) responses to either a high-protein or a high-carbohydrate breakfast and a standardized lunch in individuals with T2D. Arrows indicate when meals were consumed. Values are means ± SEMs, n = 12. *Different between breakfast and lunch,P < 0.05; **Different from corresponding meal compositions,P < 0.05; †Different by meal composition,P < 0.05; ‡Different from corresponding lunch,P = 0.07. CHO, carbohydrate breakfast; GIP, glucose-dependent insulinotropic peptide; GLP-1, glucagon-like peptide 1; PRO, protein breakfast; T2D, type 2 diabetes.