Looping Whilst Restricting Carbohydrates

Insel Gruppe AG, University Hospital Bern

Overview

To investigate the efficacy, safety and utility of hybrid closed-loop glucose control during a low carbohydrate vs. iso-energetic balanced diet in individuals with type 1 diabetes.

Closed-loop systems combining an insulin pump, a glucose sensor and a dosing algorithm that adjusts insulin delivery in a glucose-responsive manner achieve significantly better glucose control than conventional therapy in type 1 diabetes. Achieving satisfactory postprandial glucose control, however, continues to be challenging. The main limitation is the delayed pharmacokinetics and -dynamics of subcutaneously administered insulin with peak actions between 1 and 2 hours. Conversely, glucose levels typically rise within 10minutes following carbohydrate intake. This mismatch largely explains the inability of current closed-loop systems to control postprandial glucose excursions and the increased risk of late postprandial hypoglycaemia in response to both user-derived meal bolus administration and reactive algorithm-driven insulin infusion. Restricting carbohydrate may therefore significantly improve post-prandial glucose control whilst reducing hypoglycaemia. The efficacy of hybrid closed-loop operation in individuals with type 1 diabetes adhering to a low carbohydrate compared to a iso-caloric balanced diet has not been investigated to date.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

NONE

Conditions

Diabetes Type 1 Diabetes

Interventions

Low carbohydrate dietOTHER

The study intervention will be an eucaloric low carbohydrate diet (15-20 % of carbohydrates) for 2 weeks.

balanced dietOTHER

The control intervention will be a energy-matched balanced diet (50 % of carbohydrates) for 2 weeks.

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Female and male subjects aged 18 years or older * Diabetes mellitus Type 1 as definded by WHO for at least 2 years or C-peptide negative (\<100 pmol/L with concomitant blood glucose \> 4 mmol/L) * hybrid-closed-loop Insulin therapy (Minimed 670G) for at least 2 months * HbA1c \<= 9 % * The subject is willing and capable of adhering to the diet plan. Exclusion Criteria: * Physical or psychological condition likely to interfere with the normal conduct of the study and interpretation of the study results as judged by the investigator. * Excess alcohol consumption (\> 3 units/day for men, \> 2 units/day for women) * Pregnancy, planned pregnancy or breast feeding * Current participation in another clinical trial * Total daily insulin dose \>2 IU/kg/day * Nephrolithiasis * Hereditary dyslipidemia * Liver steatosis

Locations (1)

University Department of Endocrinology, Diabetology, Clinical Nutrition and Metabolism

Bern, Switzerland

Outcomes

Primary Outcomes

Percentage of time in target glucose range (3.9 - 10.0 mmol/L)

The percentage of time in target glucose range will be assessed using continuous glucose monitoring (CGM).

Time frame: 2 weeks

Secondary Outcomes

Percentage of time above target (>10 mmol/L)

The percentage of time below target (\>10 mmol/L) will be assessed using continuous glucose monitoring (CGM).

Time frame: 2 weeks

Percentage of time below target (<3.9 mmol/L)

The percentage of time below target (\<3.9 mmol/L) will be assessed using continuous glucose monitoring (CGM).

Time frame: 2 weeks

Percentage of time in hypoglycemia (<3.0 mmol/L)

The percentage of time in hypoglycemia (\<3.0 mmol/L) will be assessed using continuous glucose monitoring (CGM).

Time frame: 2 weeks

Hypoglycemia burden quantified as the area under the curve (AUC) with glucose < 3 mmol/L

Hypoglycemia burden will be assessed using continuous glucose monitoring (CGM).

Time frame: 2 weeks

Percentage of time in hyperglycemia (>16.7 mmol/L)

The percentage of time in hyperglycemia (\>16.7 mmol/L) will be assessed using continuous glucose monitoring (CGM).

Time frame: 2 weeks

Mean glucose levels (mmol/l)

Mean sensor glucose levels will be assessed using continuous glucose monitoring (CGM).

Time frame: 2 weeks

Data from ClinicalTrials.gov

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Total daily insulin dose (U)

Total daily insulin dose will be recorded by the insulin pump

Daily manual bolus Insulin dose (U)

Daily manual bolus insulin dose will be recorded by the insulin pump

Time frame: 2 weeks

2 hour postprandial glucose increment (mmol/)

2 hour postprandial glucose increment will be assessed using continuous glucose monitoring (CGM).

Time frame: 2 weeks

Within-day standard deviation of glucose (mmol/l)

Within-day standard deviation of glucose will be assessed using continuous glucose monitoring (CGM).

Time frame: 2 weeks

Within day coefficient of variation of glucose (%)

Within day coefficient of variation of glucose will be assessed using continuous glucose monitoring (CGM).

Time frame: 2 weeks

Between days coefficient of variation of glucose (%)

Between days coefficient of variation of glucose will be assessed using continuous glucose monitoring (CGM).

Time frame: 2 weeks

Night-time percentage of time in target glucose range (3.9 - 10.0 mmol/L)

Percentage of time in target glucose range will be assessed using continuous glucose monitoring (CGM).