Management of a prediabetes case with the DPP-4 inhibitor sitagliptin

DPP4 Inhibitors: Could they be One of the Solutions for COVID-19 Patients with Prediabetes?

Recent reports suggest that prediabetes is a risk factor for developing severe COVID-19 complications through underlying mechanisms involving undiagnosed sub-clinical inflammation. However, we remain without a clinical approach for managing COVID-19 in prediabetic cases. The subclinical inflammation in prediabetes is associated with elevated DPP4 levels and activity. DPP4 has pleiotropic actions, including glycaemia regulation and immuno-modulation. Recently, DPP4 has been recognised as a co-receptor for COVID-19 for entering host cells. In addition to improving glycaemia, DPP4 inhibition is associated with reduced inflammation. In this submission, we explore the potential use of DPP4 inhibitors as therapeutic agents for prediabetic patients in managing the deleterious effects of COVID-19. DPP4 inhibitors (gliptins), such as linagliptin and sitagliptin, have therapeutic effects, which have been shown to extend beyond glycaemic control with no risk of hypoglycaemia. By the nature of their mechanism of action, gliptins are not associated with hypoglycaemia, unlike their anti-glycaemic counterparts, as they mainly target postprandial glycaemia. Moreover, DPP4 inhibitors may represent a safer option for prediabetic individuals in managing prediabetes either as a prophylactic or curative treatment for COVID-19. We envisage that beyond improved glycaemic control, the use of DPP4 inhibitors would also alleviate the cytokine storm, resulting in a reduction in the severity of COVID-19 symptoms and consequently reducing the morbidity and mortality in prediabetic COVID- 19 patients.

DPP-4 inhibition resembles exercise in preventing type 2 diabetes development by inhibiting hepatic protein kinase Cε expression in a mouse model of hyperinsulinemia

OBJECTIVE

Interventions for hyperinsulinemia (HINS), an early indicator of type 2 diabetes mellitus (T2DM), can significantly reduce the T2DM risk. This study aims to determine how dipeptidyl peptidase-4 (DPP-4) inhibition prevents HINS progression to T2DM through ameliorating hepatic steatosis.

METHODS

KKay mice were used as a HINS model and they underwent exercise or received a DPP-4 inhibitor, MK0626. Hepatic steatosis was examined and liver diacylglycerol levels were determined. Human hepatic cells (LO2) were treated with MK0626 or transfected with DPP-4 siRNA. Protein kinase C ε isoform (PKCε) and DPP-4 expression and insulin receptor substrate 1 (IRS-1) phosphorylation were assessed using immunohistochemistry and western blot.

RESULTS

KKay mice developed HINS spontaneously at 7 weeks of age. Similar to exercise, MK0626 ameliorated hepatic steatosis and reduced the liver triglyceride and diacylglycerol content. Both exercise and MK0626 suppressed diacylglycerol-induced PKCε expression and restored insulin signaling, which was shown by tyrosine phosphorylation of IRS-1, in the livers of KKay mice. Additionally, silencing DPP-4 or MK0626 treatment decreased PKCε expression in LO2 cells.

CONCLUSIONS

Our data demonstrate that DPP-4 inhibition resembles exercise and effectively delays T2DM onset by suppressing hepatic PKCε expression in the HINS mouse model.

Effect of sitagliptin on energy metabolism and brown adipose tissue in overweight individuals with prediabetes: a randomised placebo-controlled trial

AIMS/HYPOTHESIS

The aim of this study was to evaluate the effect of sitagliptin on glucose tolerance, plasma lipids, energy expenditure and metabolism of brown adipose tissue (BAT), white adipose tissue (WAT) and skeletal muscle in overweight individuals with prediabetes (impaired glucose tolerance and/or impaired fasting glucose).

METHODS

We performed a randomised, double-blinded, placebo-controlled trial in 30 overweight, Europid men (age 45.9 ± 6.2 years; BMI 28.8 ± 2.3 kg/m²) with prediabetes in the Leiden University Medical Center and the Alrijne Hospital between March 2015 and September 2016. Participants were initially randomly allocated to receive sitagliptin (100 mg/day) (n = 15) or placebo (n = 15) for 12 weeks, using a randomisation list that was set up by an unblinded pharmacist. All people involved in the study as well as participants were blinded to group assignment. Two participants withdrew from the study prior to completion (both in the sitagliptin group) and were subsequently replaced with two new participants that were allocated to the same treatment. Before and after treatment, fasting venous blood samples and skeletal muscle biopsies were obtained, OGTT was performed and body composition, resting energy expenditure and [¹⁸F] fluorodeoxyglucose ([¹⁸F]FDG) uptake by metabolic tissues were assessed. The primary study endpoint was the effect of sitagliptin on BAT volume and activity.

RESULTS

One participant from the sitagliptin group was excluded from analysis, due to a distribution error, leaving 29 participants for further analysis. Sitagliptin, but not placebo, lowered glucose excursion (-40%; p < 0.003) during OGTT, accompanied by an improved insulinogenic index (+38%; p < 0.003) and oral disposition index (+44%; p < 0.003). In addition, sitagliptin lowered serum concentrations of triacylglycerol (-29%) and very large (-46%), large (-35%) and medium-sized (-24%) VLDL particles (all p < 0.05). Body weight, body composition and energy expenditure did not change. In skeletal muscle, sitagliptin increased mRNA expression of PGC1β (also known as PPARGC1B) (+117%; p < 0.05), a main controller of mitochondrial oxidative energy metabolism. Although the primary endpoint of change in BAT volume and activity was not met, sitagliptin increased [¹⁸F] FDG uptake in subcutaneous WAT (sWAT; +53%; p < 0.05). Reported side effects were mild and transient and not necessarily related to the treatment.

CONCLUSIONS/INTERPRETATION

Twelve weeks of sitagliptin in overweight, Europid men with prediabetes improves glucose tolerance and lipid metabolism, as related to increased [¹⁸F] FDG uptake by sWAT, rather than BAT, and upregulation of the mitochondrial gene PGC1β in skeletal muscle. Studies on the effect of sitagliptin on preventing or delaying the progression of prediabetes into type 2 diabetes are warranted.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02294084.

FUNDING

This study was funded by Merck Sharp & Dohme Corp, Dutch Heart Foundation, Dutch Diabetes Research Foundation, Ministry of Economic Affairs and the University of Granada.

Immunohistochemical, apoptotic and biochemical changes by dipeptidyl peptidase-4 inhibitor-sitagliptin in type-2 diabetic rats

BACKGROUND

Diabetes is a major public health problem that is rapidly increasing in prevalence. In this study, the effects of sitagliptin, a dipeptidyl peptidase-4 inhibitor, were examined on newborn diabetic rat model.

METHODS

Wistar albino newborn rats were divided into control (Ctrl), sitagliptin (Sit), diabetic and diabetic+Sit groups. On the second day after the birth, 100mg/kg streptozotocin (STZ) was administered intraperitoneally in a single dose to induce type-2 diabetes in rats. The Sit and diabetic+Sit groups were administered sitagliptin (1.5mg/kg subcutaneous) as of the day 5 for 15 days. The pancreas sections were stained with insulin (INS), glucagon (GLU), somatostatin (SS), glucagon-like peptide-1 (GLP-1) and glucagon-like peptide-1 receptor (GLP-1R) antibodies by the streptavidin-biotin peroxidase technique. The TUNEL method for apoptosis and biochemical analysis were performed in the pancreas and serum, respectively.

RESULTS

Body weight and blood glucose levels showed significant differences among all groups on days 11 and 20. In diabetic rats following treatment with sitagliptin, the area percentage of INS immunopositive cells increased while the area percentage of SS immunopositive cells decreased, insignificantly. A significant increase was observed on the area percentage of GLU, GLP-1 and GLP-1R immunopositive cells in the diabetic+Sit group when compared to the diabetic group. The area percentage of apoptotic cells was the same among all groups. While serum glutathione and malondialdehyde levels demonstrated insignificant alterations, the catalase and superoxide dismutase activity significantly changed among four groups.

CONCLUSION

According to our findings, sitagliptin may be a useful therapeutic agent to a certain extent of type-2 diabetic condition.