Effect of glycaemic excursions on QT interval in diabetes patients
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2023-09-19Author
Nadeem, Asma
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Abstract
Glucose excursions in Diabetes Mellitus patients are associated with increased risk of
cardiac morbidity and mortality (Kaul, Tarr, Ahmad, Kohner, & Chibber, 2013). With
the evidence from several clinical trials, it is understood that the hyperglycaemia
contributes to increased cardiovascular disease (CVD) risk, particularly cardiac
arrythmia due to prolongation of QT interval in Electrocardiogram (ECG). On the
other hand, there is considerable evidence from meta-analysis of clinical trials that
suggest a strong association of hypoglycaemia with prolongation of QT and CVD
outcomes. There are various other factors that are also related to QT-prolongation.
The aim of this research is to synthesise available literature to analyse and establish a
clear understanding of effect of glucose excursions on QT interval which consequently
increases CVD risk. Objective of the thesis is to study the relationship of glucose
excursions with QT-interval in electrocardiogram to understand the extent of the effect
of hyper- and hypoglycaemia on QT-interval.
A systematic approach for literature review and evidence synthesis has been employed
to collect available clinical evidence and to analyse the reported outcomes.
Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses
(PRISMA) guidelines, three databases, PubMed, Cochrane and Embase were searched
for evidence published between 2000 and 2022. The search resulted in a total of 3039
records reporting clinical trials, observational studies, case reports and meta-analysis.
After removing the duplicates (n=440), 2599 articles were selected for title and
abstract review followed 250 full paper reviews for eligibility of inclusion. A total of
77 articles were selected for review and 43 studies were selected for meta-analysis
based on data availability. The meta-analysis is performed on all data, and sub-groups
based on sub-types of diabetes and healthy population. These 43 studies were further
grouped as 17 experimental studies, 18 observational studies and 8 case reports.
A pooled analysis of experimental studies showed a positive effect in both
hypoglycaemia (Cohen’s d = 1.14; 95% CI 1.01-1.26) and hyperglycaemia (Cohen’s d = 0.5; 95% CI 0.38-0.63) compared to normal glucose levels. Hypoglycaemia has a
strong effect compared to hyperglycaemia in both healthy volunteers and diabetes
patients. QTc was also prolonged in all case reports (>460 ms). Similarly, results show
that QTc is prolonged in hypoglycaemia, reported in observational studies (Cohen’s d
= 0.58; 95% CI 0.01-1.18). It is observed that diabetic population has more QTc
prolonged cases than healthy population. QTc is more prolonged in hypoglycaemic
population (34.23 ms; 95% CI 30.71-37.75 ms) than hyperglycaemic population
(11.04 ms; 95% CI 8.30-13.78 ms).