There are more studies but look at this one (resume) (Lispro insulin reffers to "Humalog Lispro" the faster insulin avalaible):
Intramuscular versus subcutaneous injection of soluble and lispro insulin: comparison of metabolic effects in healthy subjects.
Rave K, Heise T, Weyer C, Herrnberger J, Bender R, Hirschberger S, Heinemann L.
Department of Metabolic Diseases and Nutrition, WHO Collaborating Centre for Diabetes, Heinrich Heine University, Dusseldorf, Germany. firstname.lastname@example.org
The aim of this study was to compare the glucodynamic effects of soluble insulin and the rapid acting insulin analogue insulin lispro after subcutaneous (s.c.) and intramuscular (i.m.) injection. Twelve healthy male volunteers (age 26.8 +/- 1.7 years, BMI 23.2 +/- 2.3 kg m(-2); mean +/- SD) participated in this single-centre, open-labelled, euglycaemic glucose clamp study on four different days. Soluble insulin or insulin lispro (0.2 U kg(-1)) were injected s.c. or i.m. into the thigh by syringe. The glucodynamic effects were assessed by registering the glucose infusion rates necessary to maintain blood glucose at 5.0 mmol l(-1) for the subsequent 420 min. Intramuscular injection of soluble insulin led to an earlier peak of metabolic action when compared to s.c. administered soluble insulin (tmax 138 +/- 29 vs 179 +/- 34 min; p < 0.05). The maximal metabolic effect and metabolic activity during the first 2 h after i.m. and s.c. injection of soluble insulin were comparable (GIRmax 9.7 +/- 2.3 vs 7.8 +/- 2.3 mg kg(-1) min(-1); n.s., AUC0-120min 0.60 +/- 0.18 vs 0.50 +/- 0.15 g kg(-1) 120 min; n.s.). Subcutaneous administration of insulin lispro led to a metabolic effect resembling that induced by i.m. application of soluble insulin (tmax 116 +/- 26 vs 138 +/- 29 min; n.s., GIRmax 11.1 +/- 2.3 mg vs 9.7 +/- mg kg(-1) min(-1); n.s.). However, the overall metabolic response during the first 2 h after injection was higher with s.c. insulin lispro (AUC0-120min 0.81 +/- 0.26 vs 0.60 +/- 0.18 g kg(-1) 120 min; p < 0.05). The glucodynamic activity of i.m. applied insulin lispro was comparable to that of lispro s.c.. Following i.m. injection of soluble insulin, the metabolic activity peaked more rapidly than with s.c. administration. In contrast, the metabolic effect of insulin lispro was similar with either route. The time-action profile of i.m. injected soluble insulin lies between that of s.c. applied soluble insulin and insulin lispro.
And one more:
(I paste only the remarkable info reffered to your question).
2. Which causes faster absorption - intramuscular
injection or subcutaneous?
Intramuscular (IM) injection is faster. However, IM
injection is NOT for routine use, and it has its risks.
It's definitely not for the uninitiated. It's possible
only if you are not very fat in the area, and most
likely to go right in the shoulder (deltoid) area. You
also need a longer needle to reach the muscle,
although thin persons can get to the muscle easily
with the regular subcutaneous (SC) needle.
5. Does skinfold thickness affect absorption?
The fatter the area, the slower the absorption.
Absorption may also be delayed in areas affected by
- How does exercise affect insulin absorption?
Exercise of the injection area increases absorption of
the insulin in that area. If you exercise the area that
was injected, the muscles underneath squeeze the