The dietary education trial in carbohydrate counting (DIET-CARB Study): study protocol for a randomised, parallel, open-label, intervention study comparing different approaches to dietary self-management in patients with type 1 diabetes

BMJ Open. 2019 Sep 3;9(9):e029859. doi: 10.1136/bmjopen-2019-029859.


Introduction: Clinical guidelines recommend that patients with type 1 diabetes (T1D) learn carbohydrate counting or similar methods to improve glycaemic control. Although systematic educating in carbohydrate counting is still not offered as standard-of-care for all patients on multiple daily injections (MDI) insulin therapy in outpatient diabetes clinics in Denmark. This may be due to the lack of evidence as to which educational methods are the most effective for training patients in carbohydrate counting. The objective of this study is to compare the effect of two different educational programmes in carbohydrate counting with the usual dietary care on glycaemic control in patients with T1D.

Methods and analysis: The study is designed as a randomised controlled trial with a parallel-group design. The total study duration is 12 months with data collection at baseline, 6 and 12 months. We plan to include 231 Danish adult patients with T1D. Participants will be randomised to one of three dietician-led interventions: (1) a programme in basic carbohydrate counting, (2) a programme in advanced carbohydrate counting including an automated bolus calculator or (3) usual dietary care. The primary outcome is changes in glycated haemoglobin A1c or mean amplitude of glycaemic excursions from baseline to end of the intervention period (week 24) between and within each of the three study groups. Other outcome measures include changes in other parameters of plasma glucose variability (eg, time in range), body weight and composition, lipid profile, blood pressure, mathematical literacy skills, carbohydrate estimation accuracy, dietary intake, diet-related quality of life, perceived competencies in dietary management of diabetes and perceptions of an autonomy supportive dietician-led climate, physical activity and urinary biomarkers.

Ethics and dissemination: The protocol has been approved by the Ethics Committee of the Capital Region, Copenhagen, Denmark. Study findings will be disseminated widely through peer-reviewed publications and conference presentations.

Trial registration number: Registry (NCT03623113).

Keywords: advanced carbohydrate counting; basic carbohydrate counting; carbohydrate counting; nutritional education; randomised controlled trial; type 1 diabetes.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Biomarkers / blood
  • Blood Glucose / metabolism
  • Blood Glucose Self-Monitoring
  • Diabetes Mellitus, Type 1 / blood
  • Diabetes Mellitus, Type 1 / diet therapy*
  • Diabetes Mellitus, Type 1 / physiopathology
  • Diet, Diabetic / methods*
  • Dietary Carbohydrates / pharmacology*
  • Exercise / psychology*
  • Female
  • Glycated Hemoglobin A / metabolism
  • Humans
  • Male
  • Patient Education as Topic / methods*
  • Quality of Life*
  • Self-Management / methods*


  • Biomarkers
  • Blood Glucose
  • Dietary Carbohydrates
  • Glycated Hemoglobin A

Associated data