The scientific basis for dietary recommendations in type 1 diabetes is almost lacking, with the current recommendations being based on type 2 diabetes studies. Therefore the overall purpose of this study is to improve the current evidence for dietary recommendations to people with type 1 diabetes. Study aim: To compare how a strictly low carbohydrate diet, a moderately low carbohydrate diet and a traditional diabetes diet (with higher amounts of carbohydrates) affect insulin requirements and metabolic control in individuals with type 1 diabetes. Carbohydrate intake is 50-60% of the total energy intake in the traditional diabetes diet, 30-40% in the moderately low carbohydrate diet and 15-20% in the strictly low carbohydrate diet with a minimum of 50 g carbohydrates/day. A diet with less than 50 g carbohydrates/day is usually called very low carbohydrate diet or ketogenic and will not be tested in this study. Those who wish to participate and meet the inclusion criteria (and none of the exclusion criteria) will be randomized to one of the three diets. The duration of the intervention is 6 months after which the participants will be able to choose their own diet for another 6 months. The main study visits are at baseline (screening and study start), 3, 6, 9, and 12 months. Shorter visits will be at 3 and 6 weeks. The participants will meet with a study nurse, dietitian and doctor. They will attend two carbohydrate counting courses before the start of the intervention in order to be able to match their insulin to the amount carbohydrates they eat. Participants will receive written materials about their diets with menus and recipes for better adherence to the diet. The primary endpoint is the change in insulin requirements within and between groups (for secondary endpoints please see relevant section). For assessing the different endpoints the participants will provide blood, urine and feces samples for lab analyses as well as register their insulin use, blood glucose, diet, physical activity and any blood ketones or hypoglycemia electronically or in written forms. Continuous/flash glucose monitoring (CGM/FGM) will be also used. Dietary assessment and adherence will be based on 3-4 day food diaries before every scheduled study visit.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
SINGLE
Enrollment
103
Diet with carbohydrate content 50-60% of total energy intake
Diet with carbohydrate content 30-40% of total energy intake
Diet with carbohydrate content 15-20% of total energy intake
Center for Diabetes, Academic Specialistcenter
Stockholm, Sweden
Change in insulin use
measured in international units (IU) and percentage.
Time frame: screening, day 0, 3 weeks, 6 weeks, 3 months, 6 months, 9 months, 12 months
Change in HbA1c
mmol/mol
Time frame: screening, 3 weeks, 6 weeks, 3 months, 6 months, 9 months, 12 months
Change in concentration of total cholesterol
mmol/L
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Change in concentration of triglycerides
mmol/L
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Change in concentration of HDL-cholesterol
mmol/L
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Change in concentration of LDL-cholesterol
mmol/L
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Ratio of LDL/HDL
absolute number
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Concentration of glucagon
pmol/L
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Change in markers of glycemic variability (TIR, TAR, TBR, mean sensor glucose with SD, CV)
mmol/L
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Change in weight
kg
Time frame: screening, 3 weeks, 6 weeks, 3 months, 6 months, 9 months, 12 months
Change in BMI
kg/m\^2
Time frame: screening, 3 weeks, 6 weeks, 3 months, 6 months, 9 months, 12 months
Change in abdominal circumference
cm
Time frame: screening, 3 weeks, 6 weeks, 3 months, 6 months, 9 months, 12 months
Change in concentration of p-creatinine
micromol/L
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Change in estimated Glomerular Filtration Rate (eGFR)
mL/min/1,73 m2
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Change in microalbuminuria
morning U-Alb/Crea (mg/mmol)
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Concentration of Insulin-like Growth Factor 1 (IGF-I)
microg/L
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Concentration of Insulin-like Growth Factor - binding protein 1 (IGFBP-1)
microg/L
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Concentration of leptin
microg/L
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Concentration of adiponectin
mg/L
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Concentration of interleukin 6 (IL-6)
ng/L
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Concentration of high sensitivity c-Reactive Protein (Hs-CRP)
mg/L
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Measurement of lipopolysaccharides (LPS) activity using the Limulus Amebocyte Lysate (LAL) assay
measured in endotoxin units (EU)/ml
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Concentration of glutaredoxin 1 (GRX-1)
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Concentration of Oxidized LDL
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Total Antioxidant Capacity (TAC)
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Concentration of reactive oxygen species (ROS)
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Plasma metabolites assessed by untargeted liquid chromatography - mass spectrometry (LC-MS) metabolomics
Time frame: screening, 3 months, 6 months, 9 months, 12 months
Score from the Short Form 36 (SF-36) questionnaire
The Short Form (36) Health Survey is a 36-item, patient-reported survey of patient health.The SF-36 consists of eight scaled scores, which are the weighted sums of the questions in their section. Each scale is directly transformed into a 0-100 scale on the assumption that each question carries equal weight. The lower the score the more disability. The higher the score the less disability i.e., a score of zero is equivalent to maximum disability and a score of 100 is equivalent to no disability.
Time frame: screening, 3 weeks, 6 weeks, 3 months, 6 months, 9 months, 12 months
Score from the Well-being Questionnaire-12 (WBQ-12)
This questionnaire is designed to measure general well-being, including negative well-being, energy and positive well-being. The negative well-being scale score (range 0-12) is reversed and then summed with the Energy score (range 0-12) and Positive score (range 0-12) to produce a general well-being score (range 0-36). The higher the score the greater the sense of general well-being.
Time frame: screening, 3 weeks, 6 weeks, 3 months, 6 months, 9 months, 12 months
Score from the Diabetes Treatment Satisfaction Questionnaire (DTSQ)
The DTSQ has been developed to assess patient satisfaction with diabetes treatment. The questionnaire is composed of two different factors. The first factor assesses treatment satisfaction and consists of six questions and the second factor consists of two questions, which assess the burden from hyper- and hypoglycemia. Treatment satisfaction is assessed as the sum of the scores of the six questions on the first factor (total score 36), with a higher score indicating higher treatment satisfaction.
Time frame: screening, 3 weeks, 6 weeks, 3 months, 6 months, 9 months, 12 months
Time taken to complete the Trail making test A+B
The Trail Making Test is a neuropsychological test of visual attention and task switching. It consists of two parts in which the subject is instructed to connect a set of 25 dots as quickly as possible while still maintaining accuracy. The time taken to complete the test is used as the primary performance metric, measured in seconds and or minutes.
Time frame: screening, 3 weeks, 6 weeks, 3 months, 6 months, 9 months, 12 months
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