The effects of plasma insulin and glucose on myocardial blood flow in patients with type 1 diabetes mellitus

J Am Coll Cardiol. 2005 Jul 5;46(1):42-8. doi: 10.1016/j.jacc.2005.03.056.

Abstract

Objectives: The objective of this study was to determine the impact of insulin and glucose on myocardial vasodilator function in patients with type 1 diabetes mellitus (T1DM).

Background: The relative importance of plasma insulin and glucose levels on the abnormal vasodilator function observed in T1DM is unknown.

Methods: Twenty T1DM patients underwent positron emission tomography studies to measure myocardial blood flow (MBF) (in ml/g/min) at rest (MBFr) and during adenosine (MBFa), both under baseline metabolic conditions and then during either hyperinsulinemic-euglycemic clamp (HE) (n = 10; 40 +/- 9 years, 8 female subjects, hemoglobin A1c [HbA1c] 7.8 +/- 1.1%) or hyperinsulinemic-hyperglycemic clamp (HH) (n = 10; 44 +/- 12 years, 8 female subjects, hemoglobin A1c 7.7 +/- 0.6%).

Results: Both groups showed similar MBFr and MBFa under baseline metabolic conditions (p = NS). Compared with baseline conditions, MBFr increased in the HH group (p < 0.005), whereas it did not change in the HE group. Compared with baseline conditions, MBFa decreased in the HH group (p < 0.05) but did not change in the HE group. Myocardial perfusion reserve (MPR) (MBFa/MBFr) was similar between the HE and HH groups at baseline (p = NS). During clamp, MPR tended to decrease in the HH group (p < 0.1) but did not change in the HE group (p = NS) when compared with baseline conditions. However, during the clamp MPR was significantly lower in the HH group when compared with the HE group (p < 0.0001).

Conclusions: In the short term, hyperglycemia has a deleterious effect on myocardial vasodilator function, which outweighs the beneficial effect of hyperinsulinemia.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Aged
  • Blood Glucose / physiology*
  • Coronary Circulation / physiology*
  • Coronary Vessels / diagnostic imaging
  • Coronary Vessels / physiopathology
  • Diabetes Mellitus, Type 1 / blood*
  • Diabetes Mellitus, Type 1 / diagnostic imaging
  • Diabetes Mellitus, Type 1 / physiopathology*
  • Female
  • Glucose Clamp Technique
  • Humans
  • Insulin / physiology*
  • Male
  • Middle Aged
  • Positron-Emission Tomography
  • Vasodilation / physiology*

Substances

  • Blood Glucose
  • Insulin