Abstract
Exercise tolerance tests were given to patients with non-insulin-dependent diabetes mellitus (NIDDM) to evaluate their metabolic, hormonal and sympathetic responses to exercise.
The 27 subjects had neihter proliferative retinopathy nor renal dysfunction. Most of them were engaged in light work and had not participated in physical training programs.
After fasting for about 14 hours, the subjects were loaded with bicycle ergometer exercise (1 watt/kg ideal body weight) for 20 min. Blood and urine samples were collected at 30 min after supine rest (“0 min”), at cessation of exercise (“20 min”) and at 30 min aftr ccsstion (“50 min”). Glucose, FFA, 3-hydroxybutyrate (3-OHBA), lactate, IRI, IRG, HGH, and cortisol in blood were determined. Noradrenaline (NA) and adrenaline (Adr) in urine were determined by the HPLC-THI method. The excretion rate of each catecholamine in each period was divided by the creatinine clearance value in the corresponding period.
Multiple regression analysis showed that the responses of FM from 0 to 50 min (Δ50), 3-01-IBA (Δ50), cortisol from 0 to 20 min (Δ20) and from 0 to 50 min (Δ50), and NA from the preexercise to the post-exercise periods (Δ50) were correlated with the coefficient of variation of 100 successive R-R intervals during normal breathing (CVR-R).
Thereafter two groups were selected (group A: CVR-R<2%, n=7, Group B: CVR-R 2%, n=9). Age, body mass index (BMI) and absolute work load (watt) did not differ between the groups. The levels of heart rate at 10 and 50 min after initiation of exercise, FFA at 50 min, cortisol at 20 min and NA during the post-exercise period were higher in group A. IRG levels were elevated at 20 and 50 min in group A but were unchanged in group B.
In NIDDM patients with decreased beat-to-beat variation in heart rate at rest, sympathetic responses to exercise are delayed and derangement of endocrine function may mean partial compensation for mobilizing energy substrates during exercise. The delayed hyper-responses of catecholamines may be related to cardiac arrest or high mortality reported in diabetics with autonomic neuropathy and to progression of vascular complications in diabetics.
