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

Abstract

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 (ΔQTc) during hospitalization (median, 15 days) and clinical parameters affecting ΔQTc were investigated. Results: QTc was shortened from 439 ± 24 to 427 ± 26 ms during hospitalization ( p < 0.0001). ΔQTc was positively correlated with the changes in fasting plasma glucose (ΔFPG, 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 ΔFPG was independently associated with ΔQTc. 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.

Celebrities in the heart, strangers in the pancreatic beta cell: Voltage‐gated potassium channels Kv7.1 and Kv11.1 bridge long QT syndrome with hyperinsulinaemia as well as type 2 diabetes

“…In accordance with this, glycaemic control in the form of daily insulin injections has been shown to shorten QTc in patients with T2DM. 162 Increased QTc has also been reported in patients with type 1 diabetes 163,164 , and glycaemic variability alone has been shown to increase the incidence of cardiac arrhythmia in individuals with T2DM, 165 further supporting that long-term hyperglycaemia may affect cardiac electrophysiology as well.…”