Insulin Pumps Edge Injections for T1D Glycemic Control

Researchers published the study covered in this summary on Preprints with The Lancet as a preprint that has not yet been peer reviewed.

Key Takeaways

  • In a real-world study of adults with type 1 diabetes (T1D) in Denmark, insulin pump therapy (IPT) reduced A1c by an average 3.6 mmol/mol (an average decrease of 0.33 percentage points) compared with multiple daily injections (MDI).

  • IPT also associated with a marginal increase in hospitalized diabetic ketoacidosis (DKA) but had no impact on severe hypoglycemia (SH) compared with MDI.

  • The benefit of IPT was greatest in women; older individuals; and those with higher baseline A1c levels, more diabetes complications, or also using continuous glucose monitoring.

Why This Matters

  • Few studies of IPT have examined the level of alignment between real-world experience and outcomes in randomized clinical trials.

  • The researchers used a quasi-experimental study of longitudinal, real-world data from administrative registries that allowed them to maintain high internal and external validity while examining whether the benefits seen in randomized clinical trials translate into real-life effects, both in general and among subgroup populations.

  • The authors said that this is the first study with an experimental design to compare the real-world effects of IPT and MDI.

Study Design

  • Quasi-experimental study of data collected in the Danish National Patient Registry for 24,623 adults with T1D in Denmark during 2010-2020, with an average observation time of 9.9 years. This included all Danish adults with T1Dduring the study period.

  • Among the total 243,601 person-years of observation, 16% occurred during IPT treatment.

Key Results

  • Average treatment effect on the treated (ATT) for A1c with IPT was a reduction of 3.6 mmol/mol (0.33 percentage points) compared with patients using MDI, an average 5.3% relative decrease in A1c.

  • Most of the A1c drop occurred in the first year of IPT use, with a sustained effect for up to 10 years with minimal additional changes in A1c levels

  • The ATT for DKA hospitalizations was an average 1.8 percentage point increase in patients using IPT, or 0.52 extra events per 1000 person-years compared with MDI users. Most of these events occurred during the first 3 years on IPT.

  • The ATT for SH hospitalizations was an average reduction of 0.2 percentage points compared with MDI users, a difference that was not significant.

  • The largest A1c decreases with IPT occurred in women, those with baseline A1c levels above the median, in those aged 47-58 years, and in those also using continuous glucose monitoring.

  • The rate of hospitalization for DKA was highest among those with the highest levels of A1c at baseline and among those with less education.

  • On average, 2.0% of MDI users switched to IPT per year.


  • Some laboratory data are missing because of reporting practices that were in effect during the study period.

  • The study did not include data on episodes of DKA or SH that were not severe enough to warrant hospitalization.

  • Identified ATTs are likely to have been slightly underestimated owing to treatment-staggered study design (study participants began treatment at different times).


  • The study received no commercial funding.

  • Half of the authors own shares in Novo Nordisk and one additional author serves as an advisor to and receives honoraria and research funding from Novo Nordisk. Two of these authors also reported relationships with other companies. Three coauthors had no disclosures.

This is a summary of a preprint research study, “Effects of Initiating Insulin Pump Therapy in the Real World: A Quasi-Experimental, Register-Based Study of Adults with Type 1 Diabetes,” written by researchers primarily at the Steno Diabetes Center in Copenhagen and at the Danish Center for Health Economics in Odense, Denmark on Preprints with The Lancet, provided to you by Medscape. This study has not yet been peer reviewed. The full text of the study can be found on

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