HealthDay News – For young adults with type 1 diabetes, there are differences in arrhythmic risk and cardiac repolarization during nocturnal vs daytime hypoglycemia, according to a study published online in Diabetes Care.

Peter Novodvorsky, from the University of Sheffield in the United Kingdom, and colleagues examined the effect of nocturnal and daytime clinical hypoglycemia on electrocardiogram (ECG) in 37 individuals with type 1 diabetes. Participants underwent 96 hours of simultaneous ambulatory ECG and blinded continuous interstitial glucose monitoring (CGM).

The researchers obtained 2395 hours of simultaneous ECG and CGM recordings: 159 and 1355 hours were designated hypoglycemia and euglycemia. The median duration of hypoglycemia was longer during the night than during the daytime (60 min vs 44 min; P =.020). Overall, 24.1% and 51% of nocturnal and daytime episodes, respectively, were symptomatic. 

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Compared with matched euglycemia, bradycardia was more frequent during nocturnal hypoglycemia (incidence rate ratio [IRR], 6.44; 95% CI, 6.26-6.66; P <.001). Bradycardia was less frequent during daytime hypoglycemia (IRR, 0.023; 95% CI, 0.002-0.26; P =.002), while atrial ectopics were more frequent (IRR, 2.29; 95% CI, 1.19-4.39; P =.013). During nocturnal and daytime hypoglycemia there was prolonged QTc, T-peak to T-end interval duration, and decreased T-wave symmetry.

“Our data provide further evidence that hypoglycemia is proarrhythmogenic,” the authors wrote.

Disclosures: One author disclosed financial ties to the pharmaceutical industry.

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Novodvorksy P, Bernjak A, Chow E, et al. Diurnal differences in risk of cardiac arrhythmias during spontaneous hypoglycemia in young people with type 1 diabetes [published online February 15, 2017]. Diabetes Care. doi:10.2337/dc16-2177