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OBJECTIVE: Corrected QT (QTc) prolongation is predictive of cardiovascular mortality in both the general and diabetic populations. As part of the EURODIAB Prospective Complication Study, we have assessed the 7-year incidence and risk factors of prolonged QTc in people with type 1 diabetes. RESEARCH DESIGN AND METHODS: A total of 1,415 type 1 diabetic subjects, who had normal QTc at baseline, were reanalyzed after the 7-year follow-up period. QTc >0.44 s was considered abnormally prolonged. RESULTS: Cumulative incidence of prolonged QTc was 18.7%, which is twofold higher in women than in men (24.5 vs. 13.9%, P < 0.0001). At the baseline examination, incident cases were older and less physically active than nonincident cases, had higher mean values of systolic blood pressure and HDL cholesterol, and had higher frequencies of hypertension, coronary heart disease, and distal symmetrical polyneuropathy. In multivariate logistic regression analyses, female sex and higher values of A1C and systolic blood pressure were associated with the risk of prolonged QTc, whereas physical activity and BMI within the range of 21.5-23.2 kg/m2 were protective factors. In women, association with modifiable factors, particularly BMI, was stronger than in men. CONCLUSIONS: In type 1 diabetic subjects from the EURODIAB cohort, female sex, A1C, and systolic blood pressure are predictive of prolonged QTc, whereas physical activity and BMI within the range of 21.5-23.2 kg/m2 play a protective role. These findings are clinically relevant, as they may help to identify subjects at higher risk for prolonged QTc, as well as provide potential targets for risk-lowering strategies. [ABSTRACT FROM AUTHOR]

Objective: Our aim was to assess whether severe hypoglycemic attacks were cross-sectionally associated with abnormalities of the QTc interval in type 1 diabetic patients.Research Design and Methods: The study included 3,248 type 1 diabetic patients from the EURODIAB IDDM Complications Study. Severe hypoglycemia was defined as an attack serious enough to require the help of another person. A corrected QTc interval (QTc) >0.44 s was considered abnormally prolonged.Results: Nineteen percent of patients declared one to two attacks, and 13.2% of patients had three or more attacks. Prevalence of QTc prolongation was greater in patients who experienced three or more hypoglycemic attacks. Logistic regression analysis showed that the frequency of severe hypoglycemia was independently associated with QTc prolongation, even after adjustment for diabetes complications, including autonomic neuropathy (odds ratio 1.27, 95% CI 1.02-1.58).Conclusions: We have provided evidence that severe hypoglycemic attacks are independently associated with a prolonged QTc interval in type 1 diabetic patients from the EURODIAB IDDM Complications Study. [ABSTRACT FROM AUTHOR]

Objective: The interlead variation in duration of the Q-T interval on the surface electrocardiogram (Q-T interval dispersion [QTd]) has been shown to predict mortality in type 2 diabetic patients. We evaluated the prevalence of QTd prolongation in the EURODIAB population and its relation to corrected Q-T interval (QTc), sex, age, duration of diabetes, blood glucose control, and complications. RESEARCH DESIGN AND METHODS; A total of 3,042 type 1 diabetic patients were studied. QTc was calculated according to the Bazett's formula; QTc > 0.44 s was considered abnormally prolonged. QTd was calculated using the difference between the maximum and the minimum QTc in any thoracic lead. QTd >0.080 s was considered abnormally prolonged., Results: The prevalence of an increased QTd was 7%. A significant relation was observed between QTd prolongation and diastolic blood pressure (P < 0.05). A higher prevalence of QTd prolongation was observed in patients with ischemic heart disease (P = 0.004), whereas no relationship was observed with retinopathy, albumin excretion rate, or measures of somatic and autonomic neuropathy. QTc and QTd were significantly related (P = 0.001); however, a proportion of patients with normal QTd showed a prolonged QTc (>0.44 s)., Conclusions: In patients with type 1 diabetes, QTd is associated with ischemic heart disease and diastolic blood pressure but not neuropathy. Although QTd is statistically related to duration of QTc, increased QTd and increased QTc identify different patients, and their predictive value deserves prospective evaluation.