Sv. Gelding et al., VALIDATION OF THE LOW-DOSE SHORT INSULIN TOLERANCE-TEST FOR EVALUATION OF INSULIN SENSITIVITY, Clinical endocrinology, 40(5), 1994, pp. 611-615
OBJECTIVE The assessment of insulin sensitivity requires an accurate a
nd reproducible technique. The short insulin tolerance test is a simpl
e and rapid method for screening large numbers of subjects when the fa
sting glucose level is normal. Conventionally, an insulin dose of 0.1
units/kg is used, but this may result in symptomatic hypoglycaemia in
healthy thin subjects who are insulin sensitive. In order to overcome
this problem we have employed a lower dose of insulin and have studied
the reproducibility of this modified technique comparing it with the
euglycaemic hyperinsulinaemic clamp. DESIGN Subjects were studied on t
wo separate occasions, once by a short insulin tolerance test and on a
second occasion by either a euglycaemic hyperinsulinaemic clamp (insu
lin infusion of 40 mU/m(2)/min) or a repeat short insulin tolerance te
st. PATIENTS Eleven healthy subjects were studied twice with a short i
nsulin tolerance test. A further 10 healthy subjects received a short
insulin tolerance test on one day and a euglycaemic hyperinsulinaemic
clamp study on another occasion. MEASUREMENTS Insulin sensitivity was
measured in the short insulin tolerance test using the slope of arteri
alized blood glucose concentration from 3 to 15 minutes after an intra
venous bolus of short-acting insulin, 0.05 units/kg body weight. In th
e clamp study, insulin sensitivity was derived from the average amount
of glucose infused at steady state (M) and the mean plasma insulin le
vel (I). RESULTS In the short insulin tolerance test no subject develo
ped symptomatic or biochemical hypoglycaemia, defined as a blood gluco
se <2.2 mmol/l. The (mean +/-SEM) insulin sensitivities for the 11 sub
jects studied twice were 174 /- 10 and 179 +/- 11 mu mol/l/min with a
coefficient of variation of 6.9 +/- 2.6%. There was a close correlatio
n between insulin sensitivity derived from the short insulin tolerance
test and that obtained from the euglycaemic clamp studies (so-called
M/I ratio) in the same subjects (r = 0.81; P < 0.005). CONCLUSION The
short insulin tolerance test employing 0.05 units/kg insulin is a safe
, valid and reproducible method for the assessment of insulin sensitiv
ity.