Can the upper inner side of the thigh become a new option for insulin injection?

Sites for subcutaneous insulin injections include the upper arms, abdomen, buttocks and outer sides of the thigh. No similar study has explored the feasibility of using the inner side of the thigh for insulin injection, since the 4 mm pen needles were introduced for clinical use. This study aimed to determine whether the inner side of the thigh is suitable for insulin injection.

Seventy-five patients with diabetes under insulin therapy from the Inpatient Department of Endocrinology were recruited for this non-blinded, non-randomized observational study. Subcutaneous adipose layer thicknesses of the upper, middle and lower area of the inner and outer thighs of 35 patients were measured by ultrasound, distance from the skin surface to the femoral deep vessels in 20 patients was measured, and insulin was injected at the upper inner and outer sides of the thigh in 20 patients. Pain perception, bleeding or bruising, leakage at the injection sites, blood glucose changes after insulin injection, and preferred ratings of the patients were measured.

ClinicalTrials.gov NCT02307968.

Subcutaneous adipose layer thicknesses at both the upper inner and outer thighs were more than 4 mm and the minimum distance was 10 mm. Among the 100 injections at the upper inner thigh, only three incidents of perceived pain occurred. No bleeding or bruising and leakage were observed from the inner or outer sides. Furthermore, the difference in blood glucose control between insulin injections at the inner side and outer sides was not statistically significant. Patient ratings for injections at the inner side were similar to injections at the outer side. The key limitation of this study was the small sample size of adult patients as well as the non-randomized controlled design of this study.

The upper inner thigh might be a new option for insulin injection rotation.