Table 1.

Stages of DMCM.

Classification	Stage 1 DMCM (early stage)	Stage 2 DMCM (middle stage)	Stage 3 DMCM (middle- late stage)	Stage 4 DMCM (late stage)
Symptoms of heart failure/dyspnoea	NYHA I (asymptomatic)	NYHA II	NYHA II - III	NYHA II - IV
Function (echo)	Diastolic dysfunction (HFpEF) normal systolic function	Diastolic and systolic dysfunction (HFpEF and HFrEF), EF <50%, low flow	Worsening diastolic and systolic dysfunction (HFpEF and HFrEF), EF <50%, low flow	Worsening diastolic and systolic dysfunction (HFpEF and HFrEF), EF <50%, low flow
Morphology	Increased LV mass (hypertrophy)	Increased LV mass (hypertrophy), dilatation, fibrosis	Dilatation, fibrosis, microangiopathy	Dilatation, fibrosis, micro and macro angiopathy (CAD)
Cellular mechanisms	Cardiac steatosis with increased FFA, shift of substrate metabolism	AGE formation, IR, cell death (apoptosis), necrosis, fibrosis, mild CAN, increased RAAS	Features from early and middle stages + hypertension and microvascular changes, severe CAN	Features from early and middle stages + hypertension and microvascular changes, severe CAN and CAD
Metabolism	Prediabetes, metabolic syndrome	Early diabetes, hyperglycaemia	Overt diabetes, IR	Overt diabetes, IR
Biomarkers of diabetes	Hyperglycaemia and elevated HbA1C	Hyperglycaemia and elevated HbA1C	Hyperglycaemia and elevated HbA1C	Hyperglycaemia and elevated HbA1C

CAD, coronary artery disease; NYHA, New York Heart Association functional classification of HF; EF, ejection fraction; CAN, cardiovascular autonomic neuropathy; HFpEF, HF with preserved ejection fraction; HFrEF, HF with reduced ejection fraction.