Abnormalities of the cardiovascular response to cold pressor test in type 1 diabetes. Correlation with blood glucose control.

Left-ventricular (LV) function in type 1 diabetics without clinical heart disease was compared with that found in matched normal subjects. Although diabetics had a normal LV ejection fraction (66% +/- 6%), they showed a trend toward smaller left ventricles. Their cardiovascular response to a cold pressor test was abnormal and cardiac function after the cold pressor test correlated with hemoglobin A1c levels: Average hemoglobin A1c was inversely related to ejection fraction and early filling volume and directly related to the ratio of pre-ejection period to ejection time (PEP/LVET) after a cold pressor test. Hemoglobin A1c at the time of study correlated more closely with PEP/LVET after cold pressor test than did the six-month average hemoglobin A1c level, suggesting that cardiac function fluctuates with recent changes in blood glucose control. Thus, even when diabetics have a normal LV ejection fraction, an abnormal cardiovascular response to stress may still be present, and such abnormalities correlate with blood glucose control.