Comparative study of subcutaneous, intramuscular, and intravenous administration of human insulin

Abstract

Human insulin derived from porcine insulin was given subcutaneously (s.c.), intramuscularly (i.m.), and intravenously (i.v.) to normal men. The dosage for all three routes was 0 . 075 IU/kg body weight. Diluting medium was administered by s.c. injection to obtain control values. Somatostatin (100 microgram/h) was given to inhibit pancreatic beta cell secretion. The plasma glucose responses to s.c. injection of this insulin into the anterior abdominal wall and to i.m. injection into the thigh were similar with respect to the extent, onset, and duration of effect. Plasma glucose fell from mean (+/- SE) pre-injection values of 4 . 3 +/- 0 . 15 and 4 . 4 +/- 0 . 27 mmol/l, to 3 . 06 +/- 0 . 25 and 2 . 98 +/- 0 . 16 mmol/l by 90 to 105 min for s.c. and i.m. studies, respectively, thereafter returning to mean basal level by 6 h after i.m. injection, but remaining about 0 . 5 mmol/l below basal level after s.c. injection. A much more sudden, but short-lived, hypoglycaemic response occurred after i.v. insulin, with plasma glucose failing from 4. 50 +/- 0 . 42 to 1 . 45 +/- 0 . 16 mmol/l by 25 min, returning to mean basal value after 3 1/2 h. The mean (+/- SE) peak insulin levels after s.c. and i.m. injection were 0 . 13 +/- 0 . 01 and 0 . 18 +/- 0 . 04 pmol/ml at 90 and 60 min, respectively. After i.v. injection the maximum plasma insulin concentration of 6 . 9 +/- 0 . 73 pmol/ml was seen at 2 min. No adverse side-effects were observed.