The Calculating Boluses on Multiple Daily Injections (CBMDI) study: A randomized controlled trial on the effect on metabolic control of adding a bolus calculator to multiple daily injections in people with type 1 diabetes

J Diabetes. 2017 Jan;9(1):24-33. doi: 10.1111/1753-0407.12382. Epub 2016 Apr 13.


Background: Although the insulin bolus calculator is increasingly being used by people with type 1 diabetes (T1D) on multiple daily injection (MDI) therapy, few studies have investigated its effects on glycemic control. The aim of this study was to determine whether adding this device to therapeutic intensification could further improve metabolic control.

Methods: A 4-month randomized controlled clinical trial was performed comparing subjects undergoing therapeutic intensification and either using the bolus calculator (Cb group) or not (active control [Co] group). Metabolic control, fear of hypoglycemia, and treatment acceptance were evaluated.

Results: In all, 70 people completed the study (42 in the Cb group, 28 in the Co group). There was a significant decrease in HbA1c in both the Cb and Co groups (-7 mmol/mol [-0.7 %] vs -4 mmol/mol [-0.4 %], respectively). There were no significant differences in HbA1c at baseline or the end of the study, or in the decrease in HbA1c, glycemia, or changes in blood glucose levels at the end of the study between the two groups. There was a significant increase in the number of participants with good metabolic control (HbA1c <58 mmol/mol [7.5 %]) in the Cb group (from 16.7 % to 40.5 %), but not in the Co group. The incidence of hypoglycemic events was reduced slightly but significantly only in the Cb group. There was no change in the fear of hypoglycemia at the end of the study. The bolus calculator was well accepted.

Conclusions: In T1D, adding a bolus calculator to intensive MDI resulted in a significant improvement in metabolic control and slightly decreased the number of hypoglycemic episodes. Metabolic control also improved in the Co group.

Keywords: HbA1c; bolus calculator; glycemic control; insulin therapy; type 1 diabetes.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Blood Glucose / metabolism*
  • Diabetes Mellitus, Type 1 / drug therapy*
  • Diabetes Mellitus, Type 1 / metabolism
  • Drug Administration Schedule
  • Female
  • Glycated Hemoglobin / metabolism*
  • Humans
  • Injections, Subcutaneous
  • Insulin / administration & dosage*
  • Male


  • Blood Glucose
  • Glycated Hemoglobin A
  • Insulin
  • hemoglobin A1c protein, human