Premium
QT interval, corrected for heart rate, is associated with HbA 1c concentration and autonomic function in diabetes
Author(s) -
Stern K.,
Cho Y. H.,
BenitezAguirre P.,
Jenkins A. J.,
McGill M.,
Mitchell P.,
Keech A. C.,
Donaghue K. C.
Publication year - 2016
Publication title -
diabetic medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.474
H-Index - 145
eISSN - 1464-5491
pISSN - 0742-3071
DOI - 10.1111/dme.13085
Subject(s) - medicine , autonomic function , diabetes mellitus , qt interval , cardiology , interval (graph theory) , heart rate , heart rate variability , endocrinology , blood pressure , combinatorics , mathematics
Aims To examine QT intervals corrected for heart rate ( QT c) in adolescents with Type 1 diabetes compared with control subjects, and to determine associations with metabolic control and autonomic function. Methods Resting electrocardiogram recordings of 142 adolescents with Type 1 diabetes [mean ( sd ) age 15.3 (2.0) years, diabetes duration 9.0 (3.5) years, HbA 1c 71 (17) mmol/mol or 8.7 (1.6)%] and 125 control subjects [mean ( sd ) age 15.7 (2.5) years] were used to calculate QT c duration and derive mean heart rate and heart rate variability (HRV) values. Linear and logistic regression models were used to examine the associations between QT c, metabolic control and autonomic function (HRV and pupillary function). Results QT c duration was not significantly different between subjects with Type 1 diabetes and control subjects (mean duration 392 vs 391 ms; P = 0.65). In the Type 1 diabetes group, QT c was positively associated with HbA 1c [β = 4 (95% CI 2, 6); P < 0.001] and inversely associated with severe hypoglycaemic events [β = ‐10 (95% CI ‐20,‐2); P = 0.01], less insulin/kg [β = ‐12 (95% CI ‐22, ‐2); P = 0.024] and less HRV. In the Type 1 diabetes group, QT c in the highest quintile (≥409 ms) vs quintiles 1–4 had more pupillary abnormalities (83 vs 56%; P = 0.03), lower pupillary maximum constriction velocity (4.8 vs 5.3 mm/s; P = 0.04), higher heart rate (78 vs 72 beats per min; P = 0.02) and lower HRV (standard deviation of mean NN intervals 4.0 vs 4.3 ms, P = 0.004 and root‐mean‐square difference of successive NN intervals 3.7 vs 4.1 ms; P = 0.004). Conclusions Although there are concerns about hypoglycaemia in general in people with Type 1 diabetes, chronic hyperglycaemia, rather than intermittent hypoglycaemia, appears to be more deleterious to autonomic cardiac function, even in adolescence. Longer QT c was associated with higher HbA 1c concentration, lower risk of hypoglycaemia and autonomic dysfunction. Longitudinal studies are warranted.