RESUMO
OBJECTIVE: Oxidative stress is increased in type 1 diabetes families. Since oxidative damage is a mediator of vascular injury and familial predisposition to hypertension increases the risk of hypertension and diabetic nephropathy, we studied blood pressure responses to exercise and cardiovascular risk factors in type 1 diabetes families. METHODS: Thirty-five type 1 patients, 74 first-degree relatives, and 95 healthy individuals without established coronary heart disease underwent a cycle ergometer test. Examination included medical history, lifestyle questionnaire, body weight, blood pressure, and laboratory tests [fasting plasma glucose and insulin, haemoglobin A1c (HbA1c), plasma lipids, C-reactive protein, fibrinogen, folate, plasma thiols, and albumin excretion rate]. RESULTS: Diabetic patients had higher plasma glucose, HbA1c, folate, and albuminuria, while lower plasma thiols than controls; relatives differed from controls in higher plasma total cholesterol and albuminuria, lower plasma thiols. No patient presented exercised-induced angina. Diabetic patients achieved a higher maximal exercise systolic blood pressure (similar workload); systolic pressure remained high during recovery. Relatives showed higher values of systolic pressure at peak exercise (same workload). The following were associated with an abnormal blood pressure response to exercise: diastolic blood pressure and HbA1c in the control sample; disease duration and fibrinogen in the diabetic group; plasma low-density lipoprotein (LDL) cholesterol, body mass index (BMI), housework, and plasma thiols among relatives. CONCLUSION: An abnormal blood pressure response to exercise testing has been identified for the first time in asymptomatic normotensive non-diabetic relatives of type 1 diabetics, which was associated with indices of metabolic syndrome and oxidative damage. Moreover, in healthy normotensive non-diabetic control individuals (without a family history of type 1 diabetes), the systolic blood pressure response to exercise was significantly correlated with HbA1c levels.