Aims We aimed to evaluate the effect of acute hyperglycaemia and hypoglycaemia on cardiac function in patients with type 2 diabetes (T2D) and a control group. Materials and methods In a nonrandomized interventional study, insulin-treated patients with T2D (N = 21, mean +/- SD age 62.8 +/- 6.5 years, body mass index [BMI] 29.0 +/- 4.2 kg/m(2), glycated haemoglobin [HbA1c] 51.0 +/- 5.4 mmol/mol [6.8 +/- 0.5%]) and matched controls (N = 21, mean +/- SD age 62.2 +/- 8.3 years, BMI 29.2 +/- 3.5 kg/m(2), HbA1c 34.3 +/- 3.3 mmol/L [5.3 +/- 0.3%]) underwent one experimental day with plasma glucose (PG) clamped at three different 30-minute steady-state levels: (1) fasting plasma glucose (FPG); (2) hyperglycaemia (FPG + 10 mmol/L); and (3) hyperinsulinaemic hypoglycaemia (PG