# Comparison of pharmacodynamics and pharmacokinetics of ultra‐rapid‐acting insulin aspart and rapid‐acting insulin aspart around continuous moderate intensity exercise in adults with type 1 diabetes: A randomised controlled trial

## TL;DR

This study compares how reducing doses of two types of fast-acting insulin affects blood sugar during and after exercise in people with type 1 diabetes.

## Contribution

The study shows that insulin dose reductions, not insulin type, have a greater impact on blood glucose during exercise.

## Key findings

- A 50% dose of ultra-rapid-acting insulin aspart caused similar blood glucose drops as all other conditions during exercise.
- A 50% dose of rapid-acting insulin aspart led to greater blood glucose decline than 75% doses of either insulin type.
- Differences in blood insulin levels were due to dose, not insulin type, after the first injection.

## Abstract

To compare the effects of dose reductions of ultra‐rapid‐acting insulin aspart (URA‐IAsp) and rapid‐acting insulin aspart (IAsp) on blood glucose concentrations during continuous moderate‐intensity exercise in people with type 1 diabetes (T1D).

In this double‐blind, laboratory‐controlled study, 43 adults with T1D completed four experimental visits in a randomised crossover design. Participants injected a 50% or 75% reduced dose of URA‐IAsp or IAsp with a standardised breakfast 60 min prior to 45 min of cycling at ~61% V̇O2peak. The same insulin type and dose were administered 4 h after the first injection, alongside an identical lunch meal. Venous blood samples were taken at 5‐, 10‐, and 15‐min epochs, for a total of 70 timepoints, throughout the trial day until 4 h after the second injection to determine blood glucose and insulin concentrations. The primary endpoint was the four‐way comparison of blood glucose change from exercise start to end.

Blood glucose declined during exercise to a similar extent between 50% dose URA‐IAsp (−4.0 ± 2.8 mmol L−1) and all other conditions (all p > 0.05), yet fell more in the 50% IAsp dose (−5.1 ± 3.0 mmol L−1) compared to the URA‐IAsp (−2.8 ± 3.3 mmol L−1) and IAsp (−3.4 ± 3.3 mmol L−1) 75% reduced dose conditions (both p < 0.05). Differences in blood insulin concentrations between trials were only resultant of insulin doses and not insulin type from 30 min after the first insulin injection.

Insulin dose reductions around acute moderate‐intensity exercise yield similar glucose‐lowering effects with URA‐IAsp and IAsp. The extent of dose reductions exerts greater influence on glycaemia than the type of fast‐acting insulin.