Diabetic Heart Disease

Diabetes increases heart disease risk through direct endothelial injury from hyperglycaemia (accelerating atherosclerosis), small vessel disease (microangiopathy) affecting the coronary microcirculation, diabetic cardiomyopathy (direct heart muscle damage), autonomic neuropathy (causes silent ischaemia — heart attacks without chest pain), and kidney disease (which further amplifies cardiovascular risk). Cardiovascular disease causes 50–80% of deaths in people with type 2 diabetes. All diabetics require structured annual cardiac assessment and aggressive risk factor management.

Silent ischaemia is reduced blood flow to the heart without any chest pain symptoms. In diabetics, autonomic neuropathy damages the nerve fibres that would normally transmit chest pain — so many diabetics have extensive coronary artery disease or even suffer heart attacks without any warning. Annual ECG and echocardiography can detect evidence of silent ischaemia (Q waves from unrecognised MI, wall motion abnormalities). Any breathlessness or reduced exercise tolerance in a diabetic should trigger cardiac investigation — treat it as angina until proven otherwise.

SGLT2 inhibitors (empagliflozin, dapagliflozin) lower blood glucose but were found to dramatically reduce cardiovascular mortality and heart failure — independent of glucose lowering. EMPA-REG OUTCOME showed empagliflozin reduced cardiovascular death by 38% and HF hospitalisation by 35% in diabetics with established CV disease. DAPA-HF showed dapagliflozin reduced worsening HF or CV death by 26% in HFrEF — including patients without diabetes. They are recommended for all diabetics with established CVD or high CV risk, and for all HFrEF patients regardless of diabetes status.

For multi-vessel coronary disease in diabetics, bypass surgery (CABG) is preferred over angioplasty (PCI). The FREEDOM trial (NEJM 2012, n=1,900) showed CABG reduced the 5-year composite of death, MI, and stroke by 26% versus PCI in diabetics with multi-vessel disease. Current ESC and AHA guidelines recommend CABG for diabetics with significant multi-vessel CAD. CABG achieves more complete revascularisation of the diffuse, small-vessel disease typical in diabetics. Single-vessel disease and low-complexity anatomy remain appropriate for PCI.

The general HbA1c target for most adults with type 2 diabetes is below 7.0% (53 mmol/mol). However, for patients with established cardiovascular disease, the target is individualised — stricter control (<6.5%) may benefit younger patients with recent-onset diabetes, while less strict targets (<8.0%) are appropriate for elderly patients, those with long-standing diabetes, or those with a history of severe hypoglycaemia. The ACCORD trial found that intensive glucose lowering increased mortality in high-risk patients with long-standing diabetes, so aggressive targets are not recommended for this group. All HbA1c targets should be achieved without causing significant hypoglycaemia.

Yes — most patients with diabetes and any additional risk factor (age >40, hypertension, smoking, family history of heart disease, or evidence of kidney disease) should be on a moderate-to-high intensity statin regardless of their baseline LDL cholesterol level. Diabetes itself is a powerful risk enhancer, placing most diabetic patients in the high or very high cardiovascular risk category. The target LDL cholesterol for very high-risk diabetics is below 1.4 mmol/L (55 mg/dL), and a ≥50% reduction from baseline. Statin therapy reduces major cardiovascular events by approximately 25% in diabetics, with benefits extending to those who have never had a heart attack.

Regular aerobic exercise can significantly improve cardiac function in diabetics with heart disease. Exercise improves insulin sensitivity, reduces HbA1c, lowers blood pressure, improves lipid profiles, and enhances endothelial function — all of which reduce the metabolic stress on the heart. In diabetic cardiomyopathy, structured exercise training has been shown to improve diastolic function, reduce LV stiffness, and increase exercise capacity. The ESC recommends at least 150 minutes per week of moderate-intensity aerobic activity (brisk walking, cycling, swimming) for all diabetic patients. Resistance training twice weekly provides additional metabolic benefits. Always obtain cardiac clearance before starting a new exercise programme.

All patients with type 2 diabetes should have a baseline cardiac assessment at the time of diagnosis, including ECG, blood pressure measurement, and lipid profile. If the baseline evaluation is normal, annual cardiac review is recommended — including ECG, echocardiography every 2–3 years, and cardiac risk scoring. Diabetics with established cardiovascular disease or with additional risk factors (hypertension, smoking, family history, or abnormal ECG) should be seen every 6–12 months. Any new symptom — particularly breathlessness, reduced exercise tolerance, palpitations, or atypical chest discomfort — warrants immediate cardiology evaluation, as diabetics frequently have silent ischaemia without chest pain.