Response to bicycle exercise testing in long-standing juvenile diabetes.

Submaximal bicycle ergometry was used in the evaluation of cardiac function in 22 patients with juvenile diabetes and 21 age-matched control subjects. Six patients had moderate to severe retinopathy and 2 had peripheral neuropathy. Half of the patients, but only 3 of the controls, were smokers. No differences were found in BP, serum cholesterol, triglycerides and serum creatinine levels between diabetics and controls. None had proteinuria. Patients with juvenile diabetes had higher heart rates (HR) at rest as well as during and after exercise than the healthy controls. Diabetics also had a reduced HR response to postural changes compared with the controls. Five diabetics and one control had a pathological exercise ECG (0.05 less than P less than 0.1) that may indicate early non-symptomatic coronary heart disease. The observed changes in HR may be due to autonomic neuropathy.