Chronic kidney disease and obesity bias surrogate estimates of insulin sensitivity compared with the hyperinsulinemic euglycemic clamp

Impaired incretin homeostasis in non-diabetic moderate-severe CKD

Background

Incretins are regulators of insulin secretion and glucose homeostasis that are metabolized by dipeptidyl peptidase-4 (DPP-4). Moderate-severe CKD may modify incretin release, metabolism, or response.

Methods

We performed 2-hour oral glucose tolerance testing (OGTT) in 59 people with non-diabetic CKD (eGFR<60 ml/min per 1.73 m2) and 39 matched controls. We measured total (tAUC) and incremental (iAUC) area under the curve of plasma total glucagon-like peptide-1 (GLP-1) and total glucose-dependent insulinotropic polypeptide (GIP). Fasting DPP-4 levels and activity were measured. Linear regression was used to adjust for demographic, body composition, and lifestyle factors.

Results

Mean eGFR was 38 ±13 and 89 ±17ml/min per 1.73 m2 in CKD and controls. GLP-1 iAUC and GIP iAUC were higher in CKD than controls with a mean of 1531 ±1452 versus 1364 ±1484 pMxmin, and 62370 ±33453 versus 42365 ±25061 pgxmin/ml, respectively. After adjustment, CKD was associated with 15271 pMxmin/ml greater GIP iAUC (95% CI 387, 30154) compared to controls. Adjustment for covariates attenuated associations of CKD with higher GLP-1 iAUC (adjusted difference, 122, 95% CI -619, 864). Plasma glucagon levels were higher at 30 minutes (mean difference, 1.6, 95% CI 0.3, 2.8 mg/dl) and 120 minutes (mean difference, 0.84, 95% CI 0.2, 1.5 mg/dl) in CKD compared to controls. There were no differences in insulin levels or plasma DPP-4 activity or levels between groups.

Conclusion

Incretin response to oral glucose is preserved or augmented in moderate-severe CKD, without apparent differences in circulating DPP-4 concentration or activity. However, neither insulin secretion nor glucagon suppression are enhanced.

Kidney Damage Caused by Obesity and Its Feasible Treatment Drugs

The rapid growth of obesity worldwide has made it a major health problem, while the dramatic increase in the prevalence of obesity has had a significant impact on the magnitude of chronic kidney disease (CKD), especially in developing countries. A vast amount of researchers have reported a strong relationship between obesity and chronic kidney disease, and obesity can serve as an independent risk factor for kidney disease. The histological changes of kidneys in obesity-induced renal injury include glomerular or tubular hypertrophy, focal segmental glomerulosclerosis or bulbous sclerosis. Furthermore, inflammation, renal hemodynamic changes, insulin resistance and lipid metabolism disorders are all involved in the development and progression of obesity-induced nephropathy. However, there is no targeted treatment for obesity-related kidney disease. In this review, RAS inhibitors, SGLT2 inhibitors and melatonin would be presented to treat obesity-induced kidney injury. Furthermore, we concluded that melatonin can protect the kidney damage caused by obesity by inhibiting inflammation and oxidative stress, revealing its therapeutic potential.

Glucose tolerance in patients with and without type 2 diabetes mellitus during hemodialysis

AIMS

The disposal of a glucose bolus was studied to identify glucose metabolism in patients with and without type 2 diabetes mellitus (T2DM) during their regular hemodialysis (HD) treatment.

METHODS

Plasma glucose, insulin, and c-peptide concentrations were measured during a 60 min observation phase following a rapid glucose infusion (0.5 g/kg dry weight). Glucose disposition and elimination rates were determined from kinetic analysis, and insulinogenic index was calculated. Insulin resistance (R_HOMA) was determined by homeostatic model assessment (HOMA).

RESULTS

35 HD patients (14 with T2DM) distinguished by a higher age (median: 70 vs. 55 y, p < 0.01) in T2DM patients were studied. Glucose kinetic data showed only small differences between patients with or without T2DM, but as R_HOMA measured in all patients increased, a larger fraction of glucose was removed by the extracorporeal system (r = 0.430, p = 0.01). One hour after glucose bolus injection the glucose level was not different from that before HD also in patients with T2DM (p = 0.115).

CONCLUSIONS

The larger glucose amount recovered in dialysate in patients with increasing R_HOMA indicates that impaired glucose disposal could be measured during HD using a non-invasive dialysis quantification approach without blood sampling. Glucose infusion during HD is safe also in patients with T2DM.

Chronic kidney disease attenuates the plasma metabolome response to insulin

Chronic kidney disease (CKD) leads to decreased sensitivity to the metabolic effects of insulin, contributing to protein energy wasting and muscle atrophy. Targeted metabolomics profiling during hyperinsulinemic-euglycemic insulin clamp testing may help identify aberrant metabolic pathways contributing to insulin resistance in CKD. Using targeted metabolomics profiling, we examined the plasma metabolome in 95 adults without diabetes in the fasted state (58 with CKD, 37 with normal glomerular filtration rate [GFR]) who underwent hyperinsulinemic-euglycemic clamp. We assessed heterogeneity in fasting metabolites and the response to insulin to identify potential metabolic pathways linking CKD with insulin resistance. Baseline differences and effect modification by CKD status on changes with insulin clamp testing were adjusted for confounders. Mean GFR among participants with CKD was 37.3 compared with 89.3 ml/min per 1.73 m2 among controls. Fasted-state differences between CKD and controls included abnormalities in tryptophan metabolism, ubiquinone biosynthesis, and the TCA cycle. Insulin infusion markedly decreased metabolite levels, predominantly amino acids and their metabolites. CKD was associated with attenuated insulin-induced changes in nicotinamide, arachidonic acid, and glutamine/glutamate metabolic pathways. Metabolomics profiling suggests disruption in amino acid metabolism and mitochondrial function as putative manifestations or mechanisms of the impaired anabolic effects of insulin in CKD.