Effects of COVID-19 Infection on Beta-cell Function in Euglycemic Patients

The project is monocentric, interventional, non-pharmacological, non-profit. Patients will be enrolled in hospital for confirmed COVID-19 infection (with reverse transcriptase-polymerase chain reaction on the airway swab) but with normal basal blood glucose and no previous history of diabetes or impaired fasting glucose or impaired glucose tolerance. Patients will be compared to a control group of healthy volunteers, not affected by COVID-19 and with no previous history of diabetes or impaired fasting glucose or impaired glucose tolerance. Patients will be also compared with a group of patients with type 2 diabetes but without COVID-19. Once the informed consent has been signed, the clinical parameters and biochemical parameters will be collected according to the time points provided by the protocol in positive COVID-19 patients, in healthy volunteers and in patients with type 2 diabetes. COVID-19 positive patients and healthy controls as well as patients with type 2 diabetes, will undergo a stimulation test of β-cell function (evaluation of the secretive response of insulin to the stimulation test with arginine infusion) and the monitoring of glycemic values through a professional retrospective continuous glucose monitoring. For the test, an infusion solution containing 25% arginine hydrochloride will be used, arginine is an insulinogenic amino acid, useful to verify the possible existence of damage to the cellular beta function induced by COVID-19 infection, clinically observable with changes in insulin secretory response. Given the usefulness of the test, performed for diagnostic purposes, this protocol is identified as "non-pharmacological". The test is contraindicated only in patients with severe hepatic and renal insufficiency, in all other subjects the side effects are minimal and spontaneous resolution before the end of the test (flushing 33%, oral paraesthesia 46%, nausea 12%, dizziness 14%). For the stimulation test with arginine infusion, after the basal sampling at (0 minutes), an intravenous injection of arginine 5 grams will be practiced in 60 seconds followed by serial withdrawals at +2, +5, +10 and +30 minutes. The following analytes will be assayed on the basal sample: glycosylated hemoglobin, glycaemia, insulin, pro-insulin, C-peptide, glucagon, serum inflammatory cytokines (Il1β, IL-2, IL-6, IL-7, IL-10, TNF- α, IFN-γ, MIP-1β, MCP-1, GM-CSF, G-CSF Insulin, C-peptide and glucagon will be dosed on all points of the curve.