Patients with type 1 diabetes are at risk of very low blood sugar levels (hypoglycaemia) as a severe side effect to insulin therapy, in particular subjects who have lost warning of hypoglycaemia. During hypoglycaemia a low frequent activity can be seen with electroencephalography (EEG) as cognitive function declines.

The purpose of the study is to investigate the activity in the brain, the cognitive function, and the skin temperature when patients are exposed to repeated hypoglycaemia. The results will show whether the response to hypoglycaemia will change after repeated episodes.

It is our hope that results can contribute to improved understanding of hypoglycaemic EEG changes.

Background:

Patients with type 1 diabetes are at risk of severe hypoglycaemia as a severe side effect to insulin therapy, in particular subjects who have lost warning of hypoglycaemia (hypoglycaemia unawareness). The episodes are associated with impaired quality of life and can lead to permanent brain damage and death.

During hypoglycaemia a low frequent activity can be seen with electroencephalography (EEG) as cognitive function declines. Repeated hypoglycaemic episodes result in down regulation of counter regulatory and symptomatic responses. It is not known whether a similar phenomenon is present for cerebral dysfunction as judged by EEG changes and cognitive function.

The purpose is to investigate the activity in the brain, the cognitive function, and the skin temperature when patients are exposed to repeated hypoglycaemia. The results will show whether the response to hypoglycaemia will change after repeated episodes.

The methods:

The investigators will recruit two groups of patients: Patients with hypoglycemia awareness and patients with hypoglycaemic unawareness.

The patients are exposed to hypoglycaemia on two concomitant days while the investigators record EEG and perform cognitive tests. Skin temperature is assessed by the use of thermography. If the patient has hypoglycaemic unawareness a 4 week period follows where the glycaemic control is loosened to avoid hypoglycaemia episodes and the patients is then exposed to hypoglycaemia again.

The prospect:

It is the investigators hope that results can contribute to improved understanding of hypoglycaemic EEG changes and skin temperature changes. This could be of potential benefit for patients with hypoglycaemic unawareness.

Inclusion Criteria:

• Type 1 diabetes
• Age > 18 years
• - Have had diabetes for more than 5 years
• Negative pregnancy test
• Caucasian
• Signed written informed consent

Exclusion Criteria:

• Pregnant or breastfeeding
• Epilepsy
• Self-perceived impaired hearing
• Use of antiepileptic medicine
• Use of neuroleptics within the last 6 months
• Use of benzodiazepines within the last month
• Use of betablockers
• Previous stroke or other disease in the brain
• Cardiovascular disease
• Alcohol-, drug- or medicine abuse
• Previous allergic reaction to heparin