Comparison of islet cell function, insulin sensitivity, and incretin axis between Asian-Indians with either impaired fasting glucose or impaired glucose tolerance, and normal healthy controls

Glucagon, rather than Glucagon-Like Peptide 1, Mediates Higher Post-Lunch Glucose Excursions during Breakfast Skipping in Asian Indian Patients with Uncontrolled Type 2 Diabetes Mellitus

Introduction

The effect and mechanism of skipping breakfast on glycemic control in type 2 diabetes mellitus (T2DM) in Asian-Indians is unknown.

Methods

Cross-over, within-group study recruiting 5 habitual breakfast eaters (BE) and 5 habitual breakfast skippers (BS) with uncontrolled T2DM (HbA1c 7-9%). Patients underwent testing after three days of following their usual breakfast habits and after seven days of crossing over to the other arm. Fasting values and incremental area under the curve (iAUC0-180) of post-lunch levels of glucose, insulin, C-peptide, glucagon-like peptide 1 (GLP-1), and glucagon were measured. Continuous glucose monitoring (CGM) parameters assessed were area under the curve (AUC0-180) of post-meal glucose values, 24-hour average blood glucose (ABG), time in range (TIR), and glycemic variability.

Results

BS led to significantly higher fasting (133.5 ± 34.5 mg/dl vs 110 ± 31.50 mg/dl, P = 0.009) and peak post-lunch (214.6 ± 35.07 mg/dl vs 175.4 ± 39.26 mg/dl, P < 0.001) plasma glucose, and HOMA-IR (3.05 ± 3.89 vs 2.03 ± 1.76, P = 0.007) as compared to BE. Post-lunch iAUC0-180 during BS was significantly higher for plasma glucose (7623 ± 2947.9 mg/dl × min vs 1922.4 ± 1902.1 mg/dl × min, P < 0.001), insulin (2460 ± 1597.50 mIU/ml × mins vs 865.71 ± 1735.73 mIU/ml × mins, P = 0.028), C-peptide (418.4 ± 173.4 ng/ml × mins vs 127.8 ± 117.1 ng/ml × mins, P < 0.001) and glucagon (7272.7 ± 4077 pg/ml × mins vs 4568.8 ± 2074.9 pg/ml × mins, P = 0.044) as compared to BE, while GLP-1 (1812.7 ± 883 pmol/l × mins during BS vs 1643 ± 910 pmol/l × mins during BE, P = 0.255) did not significantly differ between the two visits. CGM revealed a higher post-lunch AUC0-180 during BS. There was no difference in post-dinner AUC0-180, ABG, TIR, or glycemic variability.

Conclusion

Skipping breakfast led to higher post-lunch glucose excursions, possibly due to higher glucagon excursion and increased insulin resistance.

Inadequate Glucagon Suppression During OGTT in Prediabetes: A Systematic Review and Meta-analysis

CONTEXT

Glucagon plays a role in the development of type 2 diabetes, yet its role in prediabetes (preDM) remains uncertain.

OBJECTIVE

To evaluate glucagon levels in the fasting state and its response to glucose inhibition in preDM through meta-analysis.

METHODS

A systematic search across Pubmed, Embase, Web of Science, and Cochrane Library identified studies assessing glucagon levels during 75 g oral glucose tolerance test (OGTT) in both preDM and normal glucose tolerance (NGT) cohorts. Data on glucagon, glucose, and insulin were pooled using a random-effect model.

RESULTS

Although glucagon levels decreased in both preDM and NGT groups upon glucose challenge, glucagon levels at 0 hours, 0.5 hours, 1 hour, and 1.5 hours in preDM were significantly higher compared to NGT, despite higher glucose levels at all time points and higher insulin levels at 0 hours, 1 hour, 1.5 hours, and 2 hours during OGTT. Subgroup analysis revealed that in studies using the radioimmunoassay method, glucagon levels in preDM were higher at 0.5 hours and 1 hour than NGT, while in studies using the ELISA method, glucagon levels were similar to those of the NGT group despite higher glucose in preDM compared to NGT. Fasting glucagon level was inadequately suppressed in both impaired glucose tolerance (IGT) and impaired fasting glucose (IFG). Responsiveness to glucose inhibition was preserved in IFG, while glucagon level in IGT group at 0.5 hours after glucose intake was not suppressed and was higher than NGT.

CONCLUSION

Glucagon was not adequately suppressed during OGTT in preDM. Glucagon dysregulation is a contributing mechanism underlying both IFG and IGT.

Cardiovascular risk, fatty liver disease, glucose and insulin curve among prediabetes phenotypes in Peruvian population

Aims

To describe the cardiovascular risks, fatty liver disease, and glucose and insulin curve among prediabetes phenotypes (PPh) in Peruvian population.

Methods

A study was carried out using a secondary database of a series of patients with identified risk factors for diabetes mellitus type 2 in one clinic in Lima, Peru. Patients were divided according with the OGTT in impaired glucose 2h or IGT(Pph1), impaired fasting glucose or IFG(Pph3) or both(Pph2).

Results

259 patients were identified for analysis, 149 of whom had normal OGTT, 94 had prediabetes (36.3%), and 16 diabetes (6.2%). We found that 37(39.4%), 37(39.4%) and 20(21.2%) presented Pph1, Pph-2 and Pph-3 respectively. Most of the cardiovascular risks and hepatic function comparison showed no difference in our study sample groups. However, we found that Pph2 showed significantly higher abnormalities in HDL-c, triglycerides, hepatic steatosis, and HOMA-IR compared with normal OGTT group (p < 0.05). Interestingly, this difference was not seen with the other phenotypes. Also, hepatic steatosis was higher in Pph2 compared to Pph3 (p < 0.05). HOMA-IR was high in Phenotype 2 compared with Phenotype 1. Regarding hepatic steatosis, this was high in all prediabetes phenotypes, however we found this to be of statistical significance in Pph2 compared to Pph3 (p < 0.01).

Conclusions

In general, prediabetes phenotypes show a similar association with cardiovascular risk factors and hepatic steatosis, however, Pph2 show more differences in specific comparisons. We believe that this study is a starting point for further investigation to understand prediabetes in Peruvian population and be able to improve disease risk stratification.