Abstract 599: The Effect of Insulin-induced Hypoglycaemia on Myocardial Blood Flow in Patients With Type 1 Diabetes Mellitus
Background and Purpose: Hypoglycaemia is a frequent complication of insulin therapy in patients with diabetes mellitus (DM) and is associated with increased cardiovascular mortality. This study assessed the effect of insulin-induced hypoglycaemia on myocardial perfusion in patients with Type 1 DM.
Methods: Fourteen (37.6±10 years) volunteers with normal exercise stress echocardiograms participated. Hyperinsulinemic euglycamia (HE) was maintained for 60 minutes followed by hyperinsulinemic hypoglycaemia (HH) for a further 60 minutes. Real-time myocardial contrast echocardiography (MCE) with flash impulse imaging was used to assess the myocardial blood flow (MBF) and myocardial blood flow reserve (MBFR) before and after dipyridamole administration at baseline, HE and HH.
Results: MBFR was (2.43±0.31) at baseline and increased by 19% with insulin during HE (2.89±0.56, p = 0.003) due to an increase in the peak stress HE MBF to 60.1±11.3 dB2/s from 46.6±7.7 dB2/s (baseline), (p < 0.0001). MBFR decreased significantly during HH (2.2±0.23) in comparison to HE (p < 0.001). This was due to a reduction in peak stress HH MBF to 50.5±6.6 dB2/s (p < 0.0001) compared to HE MBF. Baseline endothelin-1 levels were elevated in comparison to controls 3-fold but did not change during HE or HH.
Conclusion: This study has shown that insulin-induced hypoglycaemia leads to a reduction in MBFR in subjects with Type 1 DM. In the presence of flow limiting coronary disease this may worsen coronary ischemia.