Prevention of Type 2 Diabetes Mellitus by L-Arginine in Patients With Metabolic Syndrome

This is a double blind, parallel, one centre study to determine if long term oral L-arginine administration is able to delay or prevent type 2 diabetes mellitus in patients with IGT and Metabolic Syndrome. Two hundred and ninety four subjects were recruited at the CardioMetabolic and Clinical Trials Unit of the San Raffaele Scientific Institute. One hundred and fourty two patients were randomized to enter the study. Patients were randomly assigned to two arms: oral L-arginine (6.4 g/die) or placebo in blind scheme. The treatment were maintained for 18 months. Visits will be performed every 3 months for clinical evaluation, blood samples, treatment supply and collect data on adverse events, if any. Furthermore, patients were contacted every month by telephone to evaluate the accurate continuation of the study and they were instructed to phone to the centre in case of possible adverse events. Inclusion criteria * Written informed consent must be obtained before any procedure of the study is done. * Male or Female aged more than 35 years. * Diagnosis of IGT after a standard Glucose Tolerance Test (OGTT, 75 g) * Moreover, in order to be considered affected by Metabolic Syndrome, they must have two or more of the following criteria: * Abdominal obesity (waist\>120 cm for man, \>88 cm for women) * Hypertriglyceridemia (\>150 mg/dl) * Low HDL cholesterol (\<40mg/dl in man, \<50 mg/dl in woman) * Hypertension (\>130 / \>85 mmHg) Exclusion criteria * Presence of type 1 or type 2 diabetes mellitus * Fasting glucose levels \>126 mg/dl * Sitting Systolic Arterial Pressure \>140mmHg, and Sitting Diastolic Arterial Pressure \>90mmHg * Pregnancy * Known renal insufficiency or creatinine levels more than 1.8 mg/dl, * Presence of chronic hepatopathy or levels of ALT and AST more than two standard deviations from normality levels * Presence of malignancy * Abuse of alcohol or abuse substances * Psychiatric disorders