Is the short insulin tolerance test safe and reproducible?
The short insulin tolerance test (SITT) is described as a simple method to measure insulin sensitivity. To investigate the safety and reproducibility of the SITT, 16 healthy volunteers underwent two SITTs within 1 week. Intravenous insulin (0.05 U kg(-1) body weight) was injected into an antecubital vein. Blood samples were collected from the contralateral antecubital vein. The insulin-induced glucose disposal rate (Kitt) was calculated from the slope of the regression line of the logarithm of blood glucose against time during the first 3-15 min. Plasma glucose concentrations fell below 2.8 mmol l(-1) in 4 of the 32 tests and below 2.2 mmol I(-1) in 1 of these 4. Five subjects had mild hypoglycaemic symptoms, three of whom had plasma glucose concentrations below 2.8 mmol l(-1) in at least one SITT. The mean Kitt was 4.2% min(-1) (range 0.8-8.4) for the first test and 3.4% min(-1) (range 0.1-6.8) for the second test. The mean within-subject coefficient of variation was 30.7%. We conclude that SITT should be applied with caution especially on insulin sensitive subjects and has poor reproducibility using 0.05 U kg(-1) body weight of insulin injection, venous sampling, uncontrolled physical activity and uncontrolled dietary composition. Whether 0.1 U kg(-1) body weight of insulin injection and arterialized venous blood sampling as in the original description of this test can improve the reproducibility of the SITT needs further investigation.
Chen
C C
CC
Department of Internal Medicine, China Medical College Hospital, Taichung, Taiwan, Republic of China.
Wang
T Y
TY
Hsu
S Y
SY
Chen
R H
RH
Chang
C T
CT
Chen
S J
SJ
D000328:Adult; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism*; D003940:Diagnostic Techniques, Endocrine / Q000009:adverse effects / Q000592:standards*; D005215:Fasting; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D007328:Insulin / Q000097:blood / Q000502:physiology*; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D015203:Reproducibility of Results; D012449:Safety
D001786:Blood Glucose; D007328:Insulin