Acarbose Cardiovascular Evaluation Trial

Inclusion Criteria: * Male or female, aged 50 years or more. * Definite CHD, defined as a, b or c below: 1. Previous myocardial infarction (MI) or Acute Coronary Syndrome (ACS), but not within the last 3 months, with any two of the following: * Typical clinical presentation * Confirmatory ECG changes * Appropriate elevation of cardiac enzymes/biomarkers 2. Previous unstable angina (UA) or Acute Coronary Syndrome (ACS), but not within the last 3 months, with any two of the following: * Typical clinical presentation * Confirmatory ECG changes * Either elevation of a cardiac biomarker or a \>50% stenosis in ≥1 major epicardial coronary artery shown on coronary angiography or CT angiography. Where stenosis is reported in a qualitative manner, the categories "moderate" and "severe" will be taken as equating to \>50% stenosis. 3. Current stable angina defined as: * Typical clinical history with symptoms occurring within the last month, and * A \>50% stenosis in ≥1 major epicardial coronary artery shown on coronary angiography or CT angiography. Where stenosis is reported in a qualitative manner, the categories "moderate" and "severe" will be taken as equating to \>50% stenosis. * Impaired glucose tolerance diagnosed on a single standard oral glucose tolerance test (OGTT) , defined as a 2-hour plasma glucose (2HPG) value ≥7.8 but \<11.1 mmol/l and a fasting plasma glucose (FPG) \<7.0 mmol/l within six months prior to enrollment. * Optimised cardiovascular drug therapy. * At least 80% adherent to single blind placebo Study Medication during the run-in period. * Provision of written informed consent. Exclusion Criteria: * Previous history of diabetes, other than gestational diabetes. * MI, unstable angina, stroke or a transient ischaemic attack (TIA) within the previous three months. * Planned or anticipated coronary, cerebrovascular or peripheral arterial revascularisation or other major surgical intervention, at the time of randomisation * New York Heart Association (NYHA) class III or IV heart failure. * Evidence of severe hepatic disease. * Evidence of severe renal impairment or an eGFR \<30 ml/min/1.73m2 (derived using the Modification of Diet in Renal Disease, MDRD, Chinese equation) * Any other condition likely to reduce adherence to the protocol e.g. alcoholism, major active psychiatric disorder, cognitive impairment or a condition likely to markedly limit life expectancy e.g. malignancy. * Pregnancy (or planned pregnancy within the next five years). * Concurrent participation in any other clinical interventional trial. Note: Patients who were treated previously with an alphaglucosidase inhibitor must have at least a three-month washout period before being randomised into the ACE trial. * Known intolerance to alpha glucosidase inhibitors or gastrointestinal problems. * Thought by the investigator for any reason to be unsuitable for participation in this clinical study.