Effects of Accidental Intramuscular Injection on Insulin Absorption in IDDM

Abstract

Recent studies have shown that with the injection technique presently recommended to diabetic patients, accidental intramuscular injection of insulin is liable to occur quite frequently. In this study, the simultaneous absorption of 125I-labeled soluble human insulin (5 U) from subcutaneous and intramuscular injection sites in the thigh and abdomen was measured for 3 h in 10 insulin-dependent diabetic subjects to evaluate the importance of accidental intramuscular injection for insulin absorption in the resting state. Injection sites were located with computed tomography of the thigh and abdomen. From a superficial part of the thigh musculature, the absorption rate was at least 50% higher than from the adjacent subcutaneous tissue, the time until 50% of the initial activity remained (t1/2) being 123 +/- 14 and greater than 180 min, respectively (P less than .001). No difference in absorption rates was found between the two tissues in the abdomen (t1/2 84 +/- 6 vs. 93 +/- 7 min, NS). The results suggest that in the thigh, accidental intramuscular injections will considerably increase the variability of insulin absorption and may impair glycemic control in insulin-dependent diabetic patients. Furthermore, the influence of accidental intramuscular injection on insulin absorption seems to vary among injection regions.

Impact of injection sites for soluble insulin on glycaemic control in Type 1 (insulin-dependent) diabetic patients treated with a multiple insulin injection regimen

“…injection of soluble insulin might be dangerous due to an elevated risk of exercise-induced hypoglycaemic episodes and for this reason that i.m. injection should be avoided [4]. During our 3-month study there was no evidence of such an elevated risk for severe hypoglycaemic episodes in the IMT group.…”

“…The absorption rate of soluble insulin from the abdominal wall is as fast as i.m. injected insulin into the thigh [4,8,13] and the absorption rate is faster than seen after s.c. injection into the thigh [6][7][8]. The consequence of a slow absorption rate of soluble insulin is relative hypoinsulinaemia after a meal and relative hyperinsulinaemia before the next meal.…”

“…Thus, approximately 50 % of the s.c. injected insulin is absorbed after 5 h compared to 2 h after intramuscular (i.m.) injection into the thigh [2,4]. The absorption rate of soluble insulin from the abdominal wall is as fast as i.m.…”

“…Thus, the purpose of the bolus component is to provide insulin delivery adequately timed to the absorption of the meal, whereas the purpose of the basal component is to provide adequate insulinisation during the night time and between meals. Obviously, insulin delivery depends on the absorption rate of the injected insulin and this has been demonstrated to vary considerably between different anatomical regions [2][3][4][5][6][7][8][9][10][11][12].…”

“…Thus, the purpose of the bolus component is to provide insulin delivery adequately timed to the absorption of the meal, whereas the purpose of the basal component is to provide adequate insulinisation during the night time and between meals. Obviously, insulin delivery depends on the absorption rate of the injected insulin and this has been demonstrated to vary considerably between different anatomical regions [2][3][4][5][6][7][8][9][10][11][12].It has been shown, that the preferred injection site for NPH insulin is the subcutaneous (s.c.) tissue of the thigh [8,[10][11][12]. Thus, this injection site produces the most constant insulin absorption rate with the smallest peak in plasma insulin [8,[10][11][12].…”