Cardiac arrhythmias in T1D and impaired awareness of hypoglycaemia
Research type
Research Study
Full title
Study to investigate the risk of cardiac arrhythmias and electrophysiological responses during spontaneous hypoglycaemia in people with type 1 diabetes and established impaired awareness of hypoglycaemia (IAH)
IRAS ID
235084
Contact name
Simon Heller
Contact email
Sponsor organisation
Sheffield Teaching Hospitals NHS Foundation Trust
Duration of Study in the UK
4 years, 0 months, 0 days
Research summary
Research Summary
Previous research in Sheffield has shown that changes on the electrical heart tracing (electrocardiography - ECG) develop during episodes of low blood sugar (hypoglycaemia) in people with type 1 diabetes (T1D) and these changes differ between day and night. We believe that these changes may, under certain conditions, lead to abnormal heart rhythms. Although life-threatening heart rhythm disturbances occur only very rarely, the risk of these events is an important clinical concern. The so called ‘dead-in-bed’ syndrome refers to a fortunately rare, but devastating condition, in which young adults with T1D (age ≤50 years) had gone to bed in apparently good health and were found dead in their undisturbed beds. Serious disturbances of heart rhythm due to hypoglycaemia have been suspected as a cause, but a direct piece of evidence is still missing. Hypoglycaemia occurs frequently at night, and it is possible that sleep has an additional influence on heart rhythm. In the current study we want to examine how does the presence of impaired awareness of hypoglycaemia (IAH), also known as the ‘hypo unawareness’ influence the ECG trace during hypoglycaemia. People with T1D (age ≤50 years, duration of diabetes at least 4 years) and IAH will undergo 96 hours of blinded continuous interstitial glucose monitoring (CGM) and Holter ECG monitoring in outpatient settings. Participants will also be asked to wear a simple sleep monitor whilst asleep. We will compare the results of this study with the already available data obtained from people with T1D but without hypo unawareness obtained from our previous study. This comparison will help us to better understand what factors influence the risk of developing serious disturbances of heart rhythm as a consequence of hypoglycaemia. This might enable us to develop new treatments to prevent this happening and prevent unnecessary deaths from heart rhythm disturbances.Summary of Results
Low blood sugars or hypoglycaemia (hypos) can cause abnormal heart rhythms in those with diabetes which increases the risk of sudden cardiac death. Hypos cause the body to produce the stress hormone adrenaline which helps in raising blood sugars back towards normal and also gives people with diabetes common symptoms of hypos such as trembling, shaking and sweating. Adrenaline levels also cause the heart to beat faster and cause changes in the blood salt potassium which the heart relies on for key functions. Higher levels of adrenaline during hypos are therefore thought to be one important way through which hypos cause heart rhythms problems in diabetes. People with type 1 diabetes (T1D) who experience multiple episodes of hypos, usually over a long time either completely or partially lose their ability to release adrenaline whilst hypo - this takes away awareness of hypo symptoms and increases risk of future hypos including severe episodes. This is called imparied awareness of hypoglycaemia (IAH) and is present in up to 20% of people with T1D. In this study we set out to test the theory that those with T1D and IAH will be protected from heart rhythm problems that occur with hypos as these individuals have either partially or fully lost their ability to produce adrenaline in response to hypos. We studied 14 people with IAH and T1D over 4 days where we monitored their heart rhythm and glucose levels as these people got on with their daily life. We found that there were marked differences between individuals in their heart response to hypos and in fact the changes in heart response to hypos differed within individuals depending on time of day. Overall, we found that in those with IAH and T1D, hypos can still cause heart changes that can increase the risk of serious heart rhythm problems. One key weakness of our study is that we were not able to recruit our desired total of at least 30 participants due to COVID-19. Future work in this field will require more participants for us to test this theory more conclusively.REC name
Yorkshire & The Humber - Sheffield Research Ethics Committee
REC reference
17/YH/0365
Date of REC Opinion
23 Nov 2017
REC opinion
Further Information Favourable Opinion