Haemodynamic studies in male diabetics

Diastolic function is reduced in adolescents with type 1 diabetes in response to exercise

OBJECTIVE

To determine whether adolescents with type 1 diabetes have left ventricular functional changes at rest and during acute exercise and whether these changes are affected by metabolic control and diabetes duration.

RESEARCH DESIGN AND METHODS

The study evaluated 53 adolescents with type 1 diabetes and 22 control adolescents. Baseline data included peak exercise capacity and body composition by dual-energy X-ray absorptiometry. Left ventricular functional parameters were obtained at rest and during acute exercise using magnetic resonance imaging.

RESULTS

Compared with nondiabetic control subjects, adolescents with type 1 diabetes had lower exercise capacity (44.7 ± 09 vs. 48.5 ± 1.4 mL/kg fat-free mass [FFM]/min; P < 0.05). Stroke volume was reduced in the diabetes group at rest (1.86 ± 0.04 vs. 2.05 ± 0.07 mL/kg FFM; P = 0.02) and during acute exercise (1.89 ± 0.04 vs. 2.17 ± 0.06 mL/kg FFM; P = 0.01). Diabetic adolescents also had reduced end-diastolic volume at rest (2.94 ± 0.06 vs. 3.26 ± 0.09 mL/kg FFM; P = 0.01) and during acute exercise (2.78 ± 0.05 vs. 3.09 ± 0.08 mL/kg FFM; P = 0.01). End-systolic volume was lower in the diabetic group at rest (1.08 ± 0.03 vs. 1.21 ± 0.04 mL/kg FFM; P = 0.01) but not during acute exercise. Exercise capacity and resting and exercise stroke volumes were correlated with glycemic control but not with diabetes duration.

CONCLUSIONS

Adolescents with type 1 diabetes have reduced exercise capacity and display alterations in cardiac function compared with nondiabetic control subjects, associated with reduced stroke volume during exercise.

Left ventricular performance during exercise in long-term type 1 diabetic men: an echocardiographic study

M-mode echocardiograms were recorded and digitized during semisupine bicycle exercise in 10 young (less than 40 years) long-term (greater than or equal to 12 years) type 1 diabetic men, without heart symptoms, and 10 controls. Recordings were done at rest, during workloads of 50 and 100 W and 1, 3 and 5 min post-exercise. The groups were comparable at rest. Exercise intervention caused a higher heart rate and systolic blood pressure response in the diabetics. Overall, diabetics had a smaller left ventricular (LV) end-diastolic dimension, but it did not change during exercise within either group; LV end-systolic dimensions (ESD), however, decreased in both. The fractional shortening, normalized peak shortening rate and systolic blood pressure/ESD ratio increased in both groups. However, fractional shortening was lower in the diabetics during peak exercise, while the two latter variables of LV systolic function were similar to the controls. Furthermore, fractional shortening during peak exercise remained lower in the diabetics even when adjusted for systolic blood pressure by covariance analysis. Therefore, the decreased LV performance during exercise in the diabetic subjects is most likely secondary to reduced LV diastolic filling, as indicated by their smaller end-diastolic dimension, rather than due to decreased contractility or a higher afterload.

Ambulatory and exercise-induced blood pressure responses in type I diabetic patients and normal subjects

We evaluated the ambulatory blood pressure (BP) readings during daily activities and compared the values with the casual office BPs in 12 type I diabetic patients and 12 age-matched, non-diabetic normal controls. The BP responses to 750 kpm/min exercise work load on bicycle ergometer were also evaluated in all the subjects. The mean ambulatory BPs were significantly higher in the diabetic patients compared with non-diabetic subjects. However, the ambulatory and casual office BPs were remarkably similar in each group. Mean peak exercise BPs were higher in the diabetics, but significantly so for diastolic BP (P less than 0.05) and mean arterial pressure (MAP) (P less than 0.01). The mean ambulatory MAP significantly correlated with the casual office MAP in both the diabetics (r = 0.75, P less than 0.005) and non-diabetics (r = 0.58, P less than 0.02). A significantly positive relationship (r = 0.87, P less than 0.001) existed between the ambulatory and peak exercise MAP in the diabetics, but not in the non-diabetic subjects. The mean peak exercise BP responses were significantly (P less than 0.01) higher in the diabetic patients with proliferative retinopathy vs. those with non-proliferative retinopathy. We conclude that casual office BPs reflect the ambulatory values in both diabetics and non-diabetics. Exaggerated BP responses to exercise are found in diabetic patients, especially in the presence of proliferative retinopathy. These findings are suggestive of possible defects in the cardiovascular, autonomic and autoregulatory mechanisms that maintain a normal MAP during daily stresses and exercise in the diabetic patients.

Exercise as a provocative test in early renal disease in type 1 (insulin-dependent) diabetes: albuminuric, systemic and renal haemodynamic responses

The value of exercise as a provocative test for early renal disease in Type 1 (insulin-dependent) diabetes was re-evaluated. Three carefully characterized groups of males were studied: 10 non-diabetic controls, 16 diabetic patients (group 1) with normal urinary albumin excretion (less than 15 micrograms/min) and 14 Albustix-negative diabetics (group 2) with increased urinary albumin excretion (15-122 micrograms/min). Assignment to a study group was made on the basis of three 24-h urine collections, and the groups were well matched for age, weight, height, and serum creatinine concentration. The two diabetic groups were similar with regard to duration of disease (13 +/- 6 versus 16 +/- 3 years), metabolic control (HbA1c: 8.4 +/- 1.4 versus 8.7 +/- 1.3%) and degree of diabetic complications (beat-to-beat variation and retinopathy). An exercise protocol of 450 and 600 kpm/min workloads was employed. In the resting state group 2 patients had elevated systolic blood pressure compared with the normal subjects (132 +/- 13 versus 119 +/- 9 mmHg), and their glomerular filtration rate was significantly reduced compared with group 1 (123 +/- 19 versus 138 +/- 15 ml/min per 1.73 m2, p less than 0.05). During exercise the urinary albumin excretion rate increased significantly in all three groups (normal subjects: 6 +/- 0.7 to 8 +/- 1.3 (microgram/min); group 1: 6 +/- 0.6 to 9 +/- 1 microgram/min and group 2: 48 +/- 10 to 113 +/- 23 micrograms/min), the relative increase being higher in group 2 (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)