Are diabetic patients less likely to feel angina than nondiabetic controls for a given extent of myocardial ischaemia?

OBJECTIVES: It is widely believed that diabetic patients with coronary artery disease have a reduced ability to feel angina. We investigated whether the diabetic patients referred for myocardial perfusion scintigraphy (MPS) are less likely to experience chest pain in daily life or during treadmill exercise than nondiabetic controls with equivalent extents of inducible hypoperfusion.
METHODS: One hundred and fifteen diabetic patients with ischaemia on single-photon emission computed tomography (SPECT) MPS were matched with 115 nondiabetic controls for age, sex, ethnic origin, method of stress used for MPS, and the extent of reversible hypoperfusion. The prevalence of chest pain from the history and during treadmill exercise (where applicable) was compared between diabetic and nondiabetic patients.
RESULTS: Of the diabetic patients, 18 (16%) were diet-controlled, 56 (49%) were treated with oral hypoglycaemic medication, and 41 (36%) used insulin. Compared with matched controls, diabetic patients were just as likely to give a history of chest pain (79 vs. 76%, P=NS), or to develop chest pain on the treadmill (31 vs. 39%, P=NS).
CONCLUSION: When carefully matched for clinical factors and the extent of ischaemia, diabetic patients referred for MPS are just as likely to experience chest pain as nondiabetic controls, whether in daily life or during treadmill exercise testing.