Multiple daily insulin injections ameliorate QT interval by lowering blood glucose levels in patients with type 2 diabetes

Background: A prolonged QT interval plays a causal role in fatal arrhythmia and is known to be a risk factor for sudden cardiac death. Although diabetic patients with microvascular complications tend to have a longer QT interval, the therapeutic effect of diabetes on the QT interval remains unclear. Here, we assessed the changes in QT interval in patients with type 2 diabetes (T2D) who received multiple daily insulin injections. Materials and methods: Patients with T2D (n = 34) who were admitted to our hospital and initiated multiple daily insulin injections for glycemic control were enrolled in this study. Clinical measurements, including electrocardiogram, were taken on admission and discharge. The QT interval was measured manually in lead II on the electrocardiogram, and corrected QT interval (QTc) was calculated using Bazett's formula. The change in QTc (Delta QTc) during hospitalization (median, 15 days) and clinical parameters affecting Delta QTc were investigated. Results: QTc was shortened from 439 +/- 24 to 427 +/- 26 ms during hospitalization (p < 0.0001). Delta QTc was positively correlated with the changes in fasting plasma glucose (Delta FPG, r = 0.55, p = 0.0008) and glycated albumin (r = 0.38, p = 0.026) following insulin therapy, but not with the final dose of insulin (r = -0.20, p = 0.26). The multiple regression analyses revealed that Delta FPG was independently associated with Delta QTc. Conclusions: Multiple daily insulin injections can ameliorate QT interval by lowering the blood glucose levels in T2D, suggesting that glycemic control is important for preventing patients with T2D from sudden cardiac death.

Automated summary

Multiple daily insulin injections can ameliorate the QT interval by lowering blood glucose levels in patients with T2D, with Delta FPG found to be positively correlated with Delta QTc. The study emphasizes the importance of glycemic control in preventing sudden cardiac death in patients with diabetes.