Accuracy and precision of low-dose insulin administration.
OBJECTIVE
To determine the lowest dose of concentrated (U100) insulin that can be reproducibly delivered.


METHODS
A telephone survey was used to determine current practices in major pediatric hospitals regarding the administration of low doses of concentrated insulin. A sensitive gravitometric technique was used to determine the error in measurement of low doses of U100 insulin by pediatric nurses and parents of diabetic children.


RESULTS
A telephone survey revealed that doses as low as 0.5 or 1.0 U (5 to 10 microL) are routinely administered in pediatric hospitals. In our study of pediatric nurses, attempts to deliver 0.5, 1.0, and 2.0 U resulted in delivered doses of 0.975 +/- 0.315, 1.638 +/- 0.376, and 2.153 +/- 0.435 U (mean +/- standard deviation of the mean), respectively. The use of 0.3-mL syringes compared to 0.5-mL syringes did not improve accuracy or precision. Taken as a group, parents of children with diabetes were more accurate (mean delivered dose of 1.063 +/- 0.276 for the 1-U dose), but the individual means ranged from 0.641 to 1.300 and coefficients of variation ranged from 5% to 33%. Only three of the seven parents could deliver 1.0 U with acceptable precision and accuracy.


CONCLUSIONS
When currently available syringes are used, insulin injections of less than 20 microL (2 U of U100) have an unacceptably large error. It is recommended that, in the inpatient setting, diluted insulin be used if the prescribed dose is less than 2.0 U.
Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD.
S J
SJ
Casella
M K
MK
Mongilio
L P
LP
Plotnick
M P
MP
Hesterberg
C A
CA
Long
D002648:Child; D003920:Diabetes Mellitus / Q000188:drug therapy*; D006801:Humans; D007267:Injections / Q000295:instrumentation / Q000451:nursing; D007328:Insulin / Q000008:administration & dosage*; D010290:Parents; D012648:Self Care; D013594:Syringes / Q000592:standards*
D007328:Insulin