QT interval prolongation and mortality in type 1 diabetic patients: a 5-year cohort prospective study. Neuropathy Study Group of the Italian Society of the Study of Diabetes, Piemonte Affiliate.

OBJECTIVE

The aim of the study was to assess the relationship between QT interval prolongation and mortality in type 1 diabetic patients.

RESEARCH DESIGN AND METHODS

Data on survival after 5 years were obtained from 316 of 379 patients (83.3%) who took part in a study on the prevalence of diabetic neuropathy and QT interval prolongation.

RESULTS

Mortality at 5 years was 6.32%. Patients who survived were significantly younger (P = 0.04), had a shorter duration of diabetes (P = 0.01), had lower systolic (P = 0.004) and diastolic (P = 0.03) blood pressure levels, and had a shorter QT interval corrected for the previous cardiac cycle length (QTc) (P = 0.000005) than subjects who died. In univariate analysis, patients had a higher risk of dying if they had a prolonged QTc (odds ratio [OR] 20.14 [95% CI 5.7-70.81) or if they were affected by autonomic neuropathy (3.55 [1.4-8.9]). QTc prolongation was the only variable that showed a significant mortality OR in multivariate analysis (24.6 [6.51-92.85]; P = 0.0000004).

CONCLUSIONS

This is the first cohort-based prospective study indicating that QTc prolongation is predictive of increased mortality in type 1 diabetic patients.