Severity and multiplicity of microvascular complications are associated with QT interval prolongation in patients with type 2 diabetes

Abstract

Aims/introduction: A prolonged QT interval plays a causal role in life-threatening arrhythmia, and becomes a risk factor for sudden cardiac death. Here, we assessed the association between microvascular complications and the QT interval in patients with type 2 diabetes.

Materials and methods: Patients with type 2 diabetes (n = 219) admitted to Nippon Medical School Hospital (Tokyo, Japan) for glycemic control were enrolled. QT interval was measured manually in lead II on the electrocardiogram, and corrected for heart rate using Bazett's formula (QTc). Diabetic neuropathy, retinopathy and nephropathy were assessed by neuropathic symptoms or Achilles tendon reflex, ophthalmoscopy and urinary albumin excretion, respectively.

Results: In univariate analyses, female sex (P = 0.025), duration of type 2 diabetes (P = 0.041), body mass index (P = 0.0008), systolic blood pressure (P = 0.0011) and receiving insulin therapy (P < 0.0001) were positively associated with QTc. Patients with each of the three microvascular complications had longer QTc than those without: neuropathy (P = 0.0005), retinopathy (P = 0.0019) and nephropathy (P = 0.0001). As retinopathy or nephropathy progressed, QTc became longer (P < 0.001 and P < 0.001 for trend in retinopathy and nephropathy, respectively). Furthermore, QTc was prolonged with the multiplicity of the microvascular complications (P < 0.001 for trend). Multiple regression analyses showed that neuropathy, nephropathy and the multiplicity of the microvascular complications were independently associated with QTc.

Conclusions: Patients with type 2 diabetes with severe microvascular complications might be at high risk for life-threatening arrhythmia associated with QT interval prolongation.

Keywords: Microvascular complications; QT interval; Type 2 diabetes mellitus.

Figure 1

Multiplicity of microvascular complications and corrected QT interval (QTc). Distribution of the QTc according to the multiplicity of microvascular complications (diabetic neuropathy, retinopathy and nephropathy). The boxes indicate the central rectangular spans from the first quartile to the third quartile (interquartile range). A segment inside the rectangle shows the median. The whiskers display the lowest datum within 1.5 interquartile range of the lower quartile and the highest datum within 1.5 interquartile range of the upper quartile. *P < 0.05 and **P < 0.01 for Dunnett's test vs patients without microvascular complications (0).