gms | German Medical Science

Question: The work was aimed at studying the lengthh of QT intervals with various levels of glycemia in two children with Type I diabetes.

Method: Simultaneous monitoring of glucose content in blood with the use of Medtronic MiniMed Continuous Glucose Monitoring System (CGMS) and monitoring of QT intervals using Holter digital system "DMS Advanced Technologies" based on automatic processing QT interval program were made. The level of glucose was determined every 5 minute during 1 and 3 day. QT monitoring was performed for three leads: MV5, MAVF and M V3 together with automatic calculation of mean QT intervals for each 5 minute periods simultaneously with glucose monitoring. The corrected QT mean value was calculated by Karjalaninen et al (1994) standard nomograms. Glucose contents up to 3.9 mmol/l were: conventionally taken as hypoglycemia, levels from 4 to 7.9 mmol/l as norm, and from 8 to 19 mmol/l as hyperglycemia.

Results: In the two observed patients hypoglycemia with glucose levels below 4 mmol/1 was observed during 5 -12 hours, mostly in sleep Reverse dependence of QTc indices on glucose levels was revealed. Table 1 [Tab. 1] shows changes in QTc values depending on glycemia. With hypoglycemia, QTc duration was 432 and 427 msec, with the norm, QTc was equal to 425 and 411 msec, and with hyperglycemia QTc was 402 and 391 msec.

Conclusion: With developing hypoglycemia there is inverse proportional dependence between hypoglycemia and QTc duration. With hyperglycemia QTc was shorter. Mean QTc index can be used as one of the markers of detecting unrevealed latent hypoglycemic states.