Time-dependent mechanisms in beta-cell glucose sensing

Influence of Fasting until Noon (Extended Postabsorptive State) on Clock Gene mRNA Expression and Regulation of Body Weight and Glucose Metabolism

The trend of fasting until noon (omission or delayed breakfast) is increasingly prevalent in modern society. This eating pattern triggers discordance between endogenous circadian clock rhythms and the feeding/fasting cycle and is associated with an increased incidence of obesity and T2D. Although the underlying mechanism of this association is not well understood, growing evidence suggests that fasting until noon, also known as an "extended postabsorptive state", has the potential to cause a deleterious effect on clock gene expression and to disrupt regulation of body weight, postprandial and overall glycemia, skeletal muscle protein synthesis, and appetite, and may also lead to lower energy expenditure. This manuscript overviews the clock gene-controlled glucose metabolism during the active and resting phases and the consequences of postponing until noon the transition from postabsorptive to fed state on glucose metabolism, weight control, and energy expenditure. Finally, we will discuss the metabolic advantages of shifting more energy, carbohydrates (CH), and proteins to the early hours of the day.

Association between breakfast frequency and insulin resistance in Korean adults with prediabetes: A nationwide population-based cross-sectional study

AIMS

This study aimed to investigate the association between breakfast frequency and insulin resistance using the triglyceride and glucose (TyG) index in Korean adults with prediabetes.

METHODS

This study used data from the 2016-2018 Korea National Health and Nutrition Examination Survey (KNHANES). A total of 16,925 participants were included in this study. Breakfast frequency was classified as 0 times, 1-4 times, and 5-7 times per week. High insulin resistance was defined as a TyG index of ≥8.5. A multivariate logistic regression analysis was performed.

RESULTS

Compared with the group whose breakfast frequency was 5-7 times per week, the odds ratio for high insulin resistance was 1.39 times (95% confidence interval (CI), 1.21-1.59) and 1.17 times (95% CI, 1.04-1.32) higher in the group whose breakfast frequency was 0 times and 1-4 times per week, respectively.

CONCLUSIONS

This study revealed that a lower frequency of breakfast consumption was significantly associated with a higher risk of insulin resistance in Korean adults with prediabetes. In the future, a large-scale prospective longitudinal study is required to establish the causal relationship between breakfast frequency and insulin resistance.

Role of High Energy Breakfast "Big Breakfast Diet" in Clock Gene Regulation of Postprandial Hyperglycemia and Weight Loss in Type 2 Diabetes

Postprandial hyperglycemia (PPHG) is strongly linked with the future development of cardiovascular complications in type 2 diabetes (T2D). Hence, reducing postprandial glycemic excursions is essential in T2D treatment to slow progressive deficiency of β-cell function and prevent cardiovascular complications. Most of the metabolic processes involved in PPHG, i.e., β-cell secretory function, GLP-1 secretion, insulin sensitivity, muscular glucose uptake, and hepatic glucose production, are controlled by the circadian clock and display daily oscillation. Consequently, postprandial glycemia displays diurnal variation with a higher glycemic response after meals with the same carbohydrate content, consumed at dusk compared to the morning. T2D and meal timing schedule not synchronized with the circadian clock (i.e., skipping breakfast) are associated with disrupted clock gene expression and is linked to PPHG. In contrast, greater intake in the morning (i.e., high energy breakfast) than in the evening has a resetting effect on clock gene oscillations and beneficial effects on weight loss, appetite, and reduction of PPHG, independently of total energy intake. Therefore, resetting clock gene expression through a diet intervention consisting of meal timing aligned to the circadian clock, i.e., shifting most calories and carbohydrates to the early hours of the day, is a promising therapeutic approach to improve PPHG in T2D. This review will focus on recent studies, showing how a high-energy breakfast diet (Bdiet) has resetting and synchronizing actions on circadian clock genes expression, improving glucose metabolism, postprandial glycemic excursions along with weight loss in T2D.

Consequences on islet and incretin hormone responses to dinner by omission of lunch in healthy men

BACKGROUND

Omission of breakfast results in higher glucose and lower insulin and incretin hormone levels after both lunch and dinner. Whether omission of lunch has a similar impact on the following meal is not known.

AIM

This study therefore explored whether omission of lunch ingestion affects glucose, islet and incretin hormones after dinner ingestion in healthy subjects.

MATERIALS & METHODS

Twelve male volunteers (mean age 22 years, BMI 22.5 kg/m2) underwent two test days in random order with standard breakfast and dinner on both days with provision or omission of standard lunch in between.

RESULTS

The results showed that throughout the 300 minutes study period, glucose, insulin, glucagon and GIP levels after dinner ingestion did not differ between the two tests. In contrast, C-peptide, and GLP-1 levels were 26%-35% higher at later time points after dinner ingestion when lunch had been omitted (P < .05).

CONCLUSION

We conclude that omission of lunch increases GLP-1 and insulin secretion and possibly also insulin clearance resulting in unchanged glucose and insulin levels after dinner ingestion.

Variable setpoint as a relaxing component in physiological control

Setpoints in physiology have been a puzzle for decades, and especially the notion of fixed or variable setpoints have received much attention. In this paper, we show how previously presented homeostatic controller motifs, extended with saturable signaling kinetics, can be described as variable setpoint controllers. The benefit of a variable setpoint controller is that an observed change in the concentration of the regulated biochemical species (the controlled variable) is fully characterized, and is not considered a deviation from a fixed setpoint. The variation in this biochemical species originate from variation in the disturbances (the perturbation), and thereby in the biochemical species representing the controller (the manipulated variable). Thus, we define an operational space which is spanned out by the combined high and low levels of the variations in (1) the controlled variable, (2) the manipulated variable, and (3) the perturbation. From this operational space, we investigate whether and how it imposes constraints on the different motif parameters, in order for the motif to represent a mathematical model of the regulatory system. Further analysis of the controller's ability to compensate for disturbances reveals that a variable setpoint represents a relaxing component for the controller, in that the necessary control action is reduced compared to that of a fixed setpoint controller. Such a relaxing component might serve as an important property from an evolutionary point of view. Finally, we illustrate the principles using the renal sodium and aldosterone regulatory system, where we model the variation in plasma sodium as a function of salt intake. We show that the experimentally observed variations in plasma sodium can be interpreted as a variable setpoint regulatory system.

Influences of Breakfast on Clock Gene Expression and Postprandial Glycemia in Healthy Individuals and Individuals With Diabetes: A Randomized Clinical Trial

OBJECTIVE

The circadian clock regulates glucose metabolism by mediating the activity of metabolic enzymes, hormones, and transport systems. Breakfast skipping and night eating have been associated with high HbA1c and postprandial hyperglycemia after lunch and dinner. Our aim was 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.

RESEARCH DESIGN AND METHODS

In a crossover design, 18 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) were randomly assigned to a test day with breakfast and lunch (YesB) and a test day with only lunch (NoB). 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 were assessed after breakfast and lunch.

RESULTS

In healthy individuals, the expression level of Per1, Cry1, Rorα, and Sirt1 was lower (P < 0.05) but Clock was higher (P < 0.05) after breakfast. In contrast, in individuals with type 2 diabetes, Per1, Per2, and Sirt1 only slightly, but significantly, decreased and Rorα increased (P < 0.05) after breakfast. In healthy individuals, the expression level of Bmal1, Rorα, and Sirt1 was higher (P < 0.05) after lunch on YesB day, whereas the other clock genes remained unchanged. In individuals with type 2 diabetes, Bmal1, Per1, Per2, Rev-erbα, and Ampk increased (P < 0.05) after lunch on the YesB day. Omission of breakfast altered clock and metabolic gene expression in both healthy and individuals with type 2 diabetes.

CONCLUSIONS

Breakfast consumption acutely affects clock and clock-controlled gene expression leading to normal oscillation. Breakfast skipping adversely affects clock and clock-controlled gene expression and is correlated with increased postprandial glycemic response in both healthy individuals and individuals with diabetes.

High-energy breakfast based on whey protein reduces body weight, postprandial glycemia and HbA1C in Type 2 diabetes

Acute studies show that addition of whey protein at breakfast has a glucose-lowering effect through increased incretin and insulin secretion. However, whether this is a long-term effect in Type 2 diabetes is unknown. Fifty-six Type 2 diabetes participants aged 58.9±4.5 years, BMI 32.1±0.9 kg/m² and HbA_1C 7.8±0.1% (61.6±0.79 mmol/mol) were randomized to one of 3 isocaloric diets with similar lunch and dinner, but different breakfast: 1) 42 g total protein, 28 g whey (WBdiet, n=19); 2) 42 g various protein sources (PBdiet, n=19); or 3) high-carbohydrate breakfast, 17 g protein from various sources (CBdiet, n=18). Body weight and HbA_1C were examined after 12 weeks. All participants underwent three all-day meal challenges for postprandial glycemia, insulin, C-peptide, intact glucagon-like peptide 1 (iGLP-1), ghrelin and hunger and satiety scores. Overall postprandial AUC_glucose was reduced by 12% in PBdiet and by 19% in WBdiet, compared with CBdiet (P<.0001). Compared with PBdiet and CBdiet, WBdiet led to a greater postprandial overall AUC for insulin, C-peptide, iGLP-1 and satiety scores, while postprandial overall AUC for ghrelin and hunger scores were reduced (P<.0001). After 12 weeks, HbA_1C was reduced after WBdiet by 0.89±0.05% (11.5±0.6 mmol/mol), after PBdiet by 0.6±0.04% (7.1±0.31 mmol/mol) and after CBdiet by 0.36±0.04% (2.9±0.31 mmol/mol) (P<.0001). Furthermore, the participants on WBdiet lost 7.6±0.3 kg, PBdiet 6.1±0.3 kg and CBdiet 3.5±0.3 kg (P<.0001). Whey protein-based breakfast is an important adjuvant in the management of Type 2 diabetes.

Fasting until noon triggers increased postprandial hyperglycemia and impaired insulin response after lunch and dinner in individuals with type 2 diabetes: a randomized clinical trial

OBJECTIVE

Skipping breakfast has been consistently associated with high HbA1c and postprandial hyperglycemia (PPHG) in patients with type 2 diabetes. Our aim was to explore the effect of skipping breakfast on glycemia after a subsequent isocaloric (700 kcal) lunch and dinner.

RESEARCH DESIGN AND METHODS

In a crossover design, 22 patients with diabetes with a mean diabetes duration of 8.4 ± 0.7 years, age 56.9 ± 1.0 years, BMI 28.2 ± 0.6 kg/m(2), and HbA1c 7.7 ± 0.1% (61 ± 0.8 mmol/mol) were randomly assigned to two test days: one day with breakfast, lunch, and dinner (YesB) and another with lunch and dinner but no breakfast (NoB). Postprandial plasma glucose, insulin, C-peptide, free fatty acids (FFA), glucagon, and intact glucagon-like peptide-1 (iGLP-1) were assessed.

RESULTS

Compared with YesB, lunch area under the curves for 0-180 min (AUC0-180) for plasma glucose, FFA, and glucagon were 36.8, 41.1, and 14.8% higher, respectively, whereas the AUC0-180 for insulin and iGLP-1 were 17% and 19% lower, respectively, on the NoB day (P < 0.0001). Similarly, dinner AUC0-180 for glucose, FFA, and glucagon were 26.6, 29.6, and 11.5% higher, respectively, and AUC0-180 for insulin and iGLP-1 were 7.9% and 16.5% lower on the NoB day compared with the YesB day (P < 0.0001). Furthermore, insulin peak was delayed 30 min after lunch and dinner on the NoB day compared with the YesB day.

CONCLUSIONS

Skipping breakfast increases PPHG after lunch and dinner in association with lower iGLP-1 and impaired insulin response. This study shows a long-term influence of breakfast on glucose regulation that persists throughout the day. Breakfast consumption could be a successful strategy for reduction of PPHG in type 2 diabetes.