Reduced Myocardial Flow Reserve in Non–Insulin-Dependent Diabetes Mellitus

OBJECTIVES: We analyzed myocardial flow reserve (MFR) in patients with non-insulin-dependent (type II) diabetes mellitus (NIDDM) without symptoms and signs of ischemia. BACKGROUND: Diminished MFR in diabetes has been suggested. However, it remains controversial whether MFR is related to glycemic control, mode of therapy or gender in NIDDM. METHODS: Myocardial blood flow (MBF) was measured at baseline and during dipyridamole loading in 25 asymptomatic, normotensive, normocholesterolemic patients with NIDDM and 12 age-matched control subjects by means of positron emission tomography and nitrogen-13 ammonia, after which MFR was calculated. RESULTS: Baseline MBF in patients with NIDDM ([mean +/- SD] 74.0 +/- 24.0 ml/min per 100 g body weight) was comparable to that in control subjects (73.0 +/- 17.0 ml/min per 100 g). However, MBF during dipyridamole loading was significantly lower in patients with NIDDM (184 +/- 99.0 ml/min per 100 g, p < 0.01) than in control subjects (262 +/- 120 ml/min per 100 g), as was MFR (NIDDM: 2.77 +/- 0.85; control subjects: 3.8 +/- 1.0, p < 0.01). A significantly decreased MFR was seen in men (2.35 +/- 0.84) compared with women with NIDDM (3.18 +/- 0.79, p < 0.05); however, no significant differences were found in terms of age, hemoglobin a1c and baseline MBF. MFR was comparable between the diet (2.78 +/- 0.80) and medication therapy groups (2.76 +/- 0.77) and was inversely correlated with average hemoglobin A1c for 5 years (r = -0.55, p < 0.01) and fasting plasma glucose concentration (r = -0.57, p < 0.01) but not age or lipid fractions. CONCLUSIONS: Glycemic control and gender, rather than mode of therapy, is related to MFR in NIDDM.