Impact of injection speed and volume on perceived pain during subcutaneous injections into the abdomen and thigh: a single-centre, randomized controlled trial.

AIM: The aim of this study was to assess pain associated with subcutaneous injection into the abdomen and thigh of different combinations of injection speeds and volumes. METHODS: The study was a single-centre, one-visit, double-blinded, randomized controlled trial in 82 adults with type 1 or type 2 diabetes receiving daily injections of insulin or glucagon-like peptide-1 (GLP-1) agonists. Participants received 17 subcutaneous injections (12 in abdomen, 5 in thigh) of saline at different injection speeds (150, 300 and 450 µl/s), with different volumes (400, 800, 1200 and 1600 µl), and two needle insertions without any injection. Pain was evaluated on a 100-mm visual analogue scale (VAS) (0 mm no pain, 100 mm worst pain) and on a yes/no scale for pain acceptability. RESULTS: Injection speed had no impact on injection pain (p = 0.833). Injection of larger volumes caused significantly more pain [VAS least square mean differences 1600 vs. 400 µl, 7 · 2 mm (95% confidence interval - CI; 4.6-9.7; p < 0.0001); 1600 vs. 800 µl, 7.2 mm (4.4-10.0; p < 0.0001); 1200 vs. 400 µl, 3.5 mm (0.4-6.6; p = 0.025) and 1200 vs. 800 µl, 3.6 mm (0.4-6.7; p = 0.027)]. Significantly more pain occurred in the thigh versus the abdomen [9.0 mm (6.7-11.3; p < 0.0001)]. CONCLUSIONS: Injection speed had no effect on injection pain, whereas higher injection volumes caused more pain. The results of this study may be of value for guiding patients to use the appropriate injection site and technique to reduce their injection pain. Furthermore, these findings may have important implications for the development of new injection devices and drug formulations for clinical practice.