Jakubowicz D, et al. – A randomized clinical trial was designed to explore the acute effect of breakfast consumption or omission on glucose homeostasis and clock gene expression in healthy individuals and individuals with type 2 diabetes. The obtained data demonstrate that breakfast consumption acutely affects clock and clock–controlled gene expression leading to normal oscillation. Moreover, breakfast skipping adversely affects clock and clock–controlled gene expression and is associated with increased postprandial glycemic response in both healthy individuals and individuals with diabetes.

Methods

• In a cross-over design, researchers randomized18 healthy volunteers and 18 volunteers with 14.5 ± 1.5 years diabetes, BMI 30.7 ± 1.1 kg/m2, and HbA1c 7.6 ± 0.1% (59.6 ± 0.8 mmol/mol) to a test day with breakfast and lunch (YesB) and a test day with only lunch (NoB).
• They evaluated postprandial clock and clock-controlled gene expression, plasma glucose, insulin, intact glucagon-like peptide-1 (iGLP-1), and dipeptidyl peptidase IV (DPP-IV) plasma activity after breakfast and lunch.

Results

• The expression level of Per1, Cry1, Ror α, and Sirt1 was lower (P < 0.05) but Clock was higher (P < 0.05) after breakfast in healthy individuals.
• On the other hand, in individuals with type 2 diabetes, Per1, Per2, and Sirt1 only slightly, but significantly, decreased and Ror α increased (P < 0.05) after breakfast. In healthy individuals, the expression level of Bmal1, Ror α, and Sirt1 was higher (P < 0.05) after lunch on YesB day, whereas the other clock genes remained unchanged.
• The data showed that Bmal1, Per1, Per2, Rev-erb α, and Ampk increased (P < 0.05) after lunch on the YesB day in individuals with type 2 diabetes.
• Remarkably, omission of breakfast altered clock and metabolic gene expression in both healthy and individuals with type 2 diabetes.