Almost all people who have had type 1 diabetes for 5 years have a defect in secretion of the hormone Glucagon. This hormone is involved in the body's response to low blood glucose (hypoglycaemia). It works by releasing glucose stores from the liver to bring the blood glucose back to normal. This defect therefore increases the risk of severe hypoglycaemia. The reason for this Glucagon defect in people with Type 1 diabetes is currently unknown. This study aims to look at the Glucagon response to hypoglycaemia in 24 people with type 1 diabetes to ascertain whether tight blood glucose control over a period of time improves this response. The investigators aim to achieve good blood glucose control using new generation Automated Insulin Delivery systems (AIDs). This system is made of: an insulin pump, a continuous glucose monitor (CGM) and an algorithm that allows adjustment of insulin delivery based on the blood glucose readings from the CGM. This is the most up to date technology that there is in the management of type 1 diabetes. However, people using this technology often still have problems with high blood glucose after eating. To ensure a very good blood glucose control participants will also follow a low carbohydrate diet to prevent this blood glucose rise after meals. The Glucagon response to low blood glucose will be measured at zero and eight months using the hyperinsulinaemic hypoglycaemic clamp technique.
This is a feasibility pilot study involving 24 participants with type 1 diabetes. Participants will be recruited from the local type 1 diabetes clinic and insulin pump waiting list. Each participant will enter the trial for a period of 8 months. The investigators aim to test if maximising time in glycaemic range (blood glucose 3.9-10 mmol/L) will restore the glucagon response to insulin-induced hypoglycaemia. After signing informed consent participants will be screened for eligibility against the inclusion and exclusion criteria. Those who are eligible will have an initial 20-day period of baseline blood glucose data collection. This will be achieved using a blinded continuous glucose monitoring (CGM) device. Participants will continue on their pre-trial diabetes care during this period and will be required to monitor their own blood glucose as normal. The participants will be split into two groups using stratified sampling to match for: age, gender and BMI. Group 1 will be the control group. Participants in this group will continue on standard diabetes care for the duration of the trial. Participants will be required to undertake two further periods of blinded CGM monitoring at 4 and 8 months. Group 2 will be the intervention group. Participants in this group will be placed on the automated insulin delivery (AID) system and asked to follow a low carbohydrate diet of 30-40g of carbohydrate per main meal portion. The AID system will consist of: a Tandem t:slim X2 insulin pump with control IQ technology and a Dexcom G6 continuous glucose monitor. After receiving training on the use of the devices these participants will enter a 2 week study run-in period to become accustomed to the devices and so that device settings can be optimised. As a safety measure these participants will be asked to measure blood ketones at least once daily throughout the trial. Study staff will monitor the data from the participants study devices throughout the trial and adjust settings as required to maximise time in glycaemic range. At the beginning and end of the trial all participants will undergo a hyperinsulinaemic hypoglycaemic clamp study to measure their counterregulatory hormone response to hypoglycaemic. Participants will also undergo cognitive tests and assessment of hypoglycaemic awareness during each clamp study.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
24
Participants will commence on a primed insulin infusion at a constant rate of 60mU/m2/min along with a variable rate 20% glucose infusion. Participants will have their blood glucose monitored every 5 minutes. The glucose infusion will be altered to achieve the desired blood glucose plateaus of: 5mmol/l, 3mmol/l and 2.5mmol/l. Each plateau will be held for 40 minutes. During each plateau blood samples will be taken on three occasions for: glucagon, cortisol, adrenaline, noradrenaline, D2 glucose and D5 glycerol. On two occasions during each plateau participants will complete the Edinburgh hypoglycaemia scale and the following cognitive tests: trail making test, digit span test, digit symbol substitution test and four choice reaction time test. At the end of the clamp study the insulin infusion will be discontinued and the blood glucose will be allowed to rise to the normal range. Participants will consume lunch before leaving the clinical research facility.
Insulin pump with a built-in algorithm that allows it to work with a CGM device to adjust insulin delivery based on CGM readings.
Continuous glucose monitoring device that sends data to the insulin pump to allow the algorithm to adjust insulin delivery. Participants are able to see the glucose data from the device when it is used in open mode.
30-40g of carbohydrate per main meal portion.
Allows data on blood glucose to be collected without values altering the behaviour of the participant. Participants have to continue to monitor their own blood glucose while wearing the device in the blinded mode.
These studies will take place at the same time as the hyperinsulinaemic hypoglycaemic clamp studies. Participants will receive a priming dose of each stable isotope followed by a continuous infusion for the remainder of the clamp study.
Edinburgh Royal Infirmary/University of Edinburgh
Edinburgh, United Kingdom
The Change in Plasma Glucagon Levels (Pmol/L) Measured During Normoglycaemic and Hypoglycaemia
The delta glucagon concentration (pmol/L) from plateau 1 (normoglycaemia- 5.0 mmol/L) to plateau 3 (hypoglycaemia- 2.5 mmol/L). The physiological response in health would be for an increase in glucagon secretion from normo- to hypoglycaemia.
Time frame: Clamp 1 at baseline and clamp 2 at 8 months
Time in Glycaemic Range (3.9-10mmol/L)
Percentage time spent in target glycaemic range.
Time frame: Baseline (study entry), midpoint at 4 months and endpoint at 8 months
Time Spent Below the Target Glycaemic Range (<3.9mmol/L)
Percentage of time spent below the target glycaemic range
Time frame: Baseline (study entry), midpoint at 4 months and endpoint at 8 months
Time Spent Above the Target Glycaemic Range (>10mmol/L)
Percentage of time spent above the target glycaemic range
Time frame: Baseline (study entry), midpoint at 4 months and endpoint at 8 months
The Change in Plasma Cortisol (ng/mL) Levels Measured During Normoglycaemic and Hypoglycaemia
Delta cortisol from P1 (5.0 mmol/L) to P3 (2.5 mmol/L)
Time frame: Clamp 1 at baseline and clamp 2 at 8 months
The Change in Plasma Adrenaline (pg/mL) Levels Measured During Normoglycaemic and Hypoglycaemia
Delta adrenaline from plateau 1 (5mmol/L) to plateau 3 (2.5 mmol/L)
Time frame: Clamp 1 at baseline and clamp 2 at 8 months
The Change in Plasma Noradrenaline (pg/mL) Levels Measured During Normoglycaemic and Hypoglycaemia
The change in noradrenaline concentration from plateau 1 (5 mmol/L) to plateau 3 (2.5 mmol/L).
Time frame: Clamp 1 at baseline and clamp 2 at 8 months
Endogenous Glucose Production
The change in the glucose rate of appearance from plateau 1 (5mmol/L) to plateau 3 (2.5 mmol/L)
Time frame: Clamp 1 at baseline and clamp 2 at 8 months
HbA1c
Delta HbA1c from baseline to study endpoint.
Time frame: Baseline (study entry) endpoint (8 months)
Change in Quality of Life at Trial Entry and End.
Measured using the EQ5D-5L- -VAS. Number on scale of 0-100 to assess wellbeing on that day. 100 being the most well.
Time frame: Baseline (study entry) endpoint (8 months)
Change in Emotional Distress Related to Diabetes at Trial Entry and End.
Diabetes Distress Scale (DDS-1)- a 28-item self-reporting scale. Each item can be scored from 1 (not a problem) to 6 (a very serious problem). This questionnaire will be completed at study entry and study end. Data presented is the DDS total score.
Time frame: Baseline (study entry) endpoint (8 months)
Change in Fear of Hypoglycaemic
Measured using the Hypoglycaemia Fear Survey (HFS)- this survey consists of two subscales- Baseline (study entry) endpoint (8 months) Behaviour and Worry. There are 28 items in the survey that the participant ranks from Never (0) to Almost Always (4). Higher scores indicate fear of hypoglycaemia. In the Behaviour subscale the lowest possible score in 0 and the highest possible score is 60. In the Worry subscale the lowest possible score is 0 and the highest is 72. Participants will complete this questionnaire at study entry and study end.
Time frame: Baseline (study entry) endpoint (8 months)
Change in Confidence of Managing Hypoglycaemia
Measured using the Hypoglycaemic Confidence Scale- this is a 9 item scale. The participant rates each item from Not Confident at All to Very Confident. Participants will complete this questionnaire at study entry and study end. Higher scores mean more confidence. 'Not confident' at lower end of scale scored as 1 and 'very confident' at top of the scale scored as 4. Min score is 9 and max score is 36.
Time frame: Baseline (study entry) endpoint (8 months)
Hypoglycaemia Awareness
Measured during each clamp study using the Edinburgh Hypoglycaemic Scale- this is a 17 item scale of symptoms of hypoglycaemia. The participant ranks on a scale from Not at all (1) to A Great Deal (7) whether they are experiencing each symptom at the time of the questionnaire being completed. Higher scores mean more hypoglycaemia symptoms. The lowest possible score is 0 and the highest possible score is 119.
Time frame: Clamp 1 - study entry, clamp 2 - 8 months
Trial Making Test
Measured during each plateau in a stepped hypoglycaemic clamp study at study entry and study end. Delta score plateau 1 (5 mmol/L) to plateau 3 (2.5 mmol/L) compared between clamp studies. Participants are timed completing the test. Higher scores indicate a longer time to complete the test.
Time frame: Clamp 1- study entry, clamp 2 - 8 months
Digit Span Test
Measured during each plateau in a stepped hypoglycaemic clamp study at study entry and study end. Difference in change in score from plateau 1 (5mmol/L) to plateau 3 (2.5 mmol/L) compared between clamp studies. Lower scores mean more errors. Forwards- participant repeats the numbers as read. Backwards- the participant repeats the numbers backwards.
Time frame: Clamp 1- study entry, clamp 2 - 8 months
Digit Symbol Substitution Test
Measured during each plateau in a stepped hypoglycaemic clamp study at study entry and study end. Difference in score between plateau 1 (5.0 mmol/L) and plateau 3 (2.5 mmol/L) compared between clamp studies. Given 90 seconds to complete as many items as possible. Higher scores mean more items completed in the allotted time.
Time frame: Clamp 1- study entry, clamp 2 - 8 months
Four Choice Reaction Time Test
Measured during each plateau in a stepped hypoglycaemic clamp study at study entry and study end. Difference in score between plateau 1 (5.0mmol/L) and plateau 3 (2.5 mmol/L) compared between clamp studies. Higher scores mean more time taken to complete the task.
Time frame: Clamp 1- study entry, clamp 2 - 8 months
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