Diabetes Care, Vol 20, Issue 12 1814-1821, Copyright © 1997 by American Diabetes Association
Exercise responses in patients with IDDM
AM Nugent, IC Steele, F al-Modaris, S Vallely, A Moore, NP Campbell, PM Bell, KD Buchanan, ER Trimble and DP Nicholls
Department of Medicine, Royal Victoria Hospital, Belfast, Northern Ireland, U.K.
OBJECTIVE: The hemodynamic, respiratory, and metabolic responses to
exercise were studied in IDDM patients and control subjects to detect
diabetic cardiomyopathy. RESEARCH DESIGN AND METHODS: Eight subjects aged
25-40 years with diabetes of at least 10 years' duration were compared with
eight control subjects aged 21-46 years. All subjects underwent a
progressive incremental bicycle exercise test with measurement of gas
exchange, blood glucose, lactate, fat metabolite, and catecholamine levels
and two steady-state exercise tests with measurement of cardiac output by a
CO2 rebreathing method. A new first-pass radionuclide method was used to
measure cardiac ejection fractions (EFs) at rest, peak exercise, and
steady-state exercise. RESULTS: The peak achieved oxygen consumption was
similar in the diabetic and control subjects (29.9 [25.1-34.6] and 31.4
[26.9-35.9] ml.min-1.kg-1, respectively; mean [95% CI]). There were no
significant differences in heart rate, double product, ventilation,
respiratory exchange ratio, or ventilatory equivalents for oxygen and CO2
during the incremental test. Glucose levels were higher in the diabetic
subjects, but there were no significant differences in levels of lactate,
catecholamines, free fatty acids, glycerol, or beta-hydroxybutyrate. Left
ventricular EF fell from rest to peak exercise within the diabetic group
(66.0% [59.6-72.4] at rest; 53.6% [45.6-61.6] at peak; P < 0.05) but
this did not differ significantly from the control group (58.7% [52.3-65.1]
at rest; 60.3% [48.9-71.7] at peak). Right ventricular EFs were similar in
each group, and there was no reduction in peak filling rate to suggest
diastolic dysfunction. The cardiac output responses to exercise were also
similar in the two groups. CONCLUSIONS: There is no evidence of impairment
of the exercise response in subjects with long-standing diabetes, and the
apparent fall in left ventricular EF at peak exercise could be related to
hemodynamic adaptation.