Abstract
Objective To compare the dynamic insulin secretion and sensitivity
test (DISST) with the euglycaemic clamp in individuals undergoing open
Roux-en-Y gastric bypass (RYGB) surgery prior-to and one month after
surgery.
Methods Insulin sensitivity in individuals with obesity undergoing
RYGB was studied with DISST and a euglycaemic hyperinsulinaemic clamp.
Results Eleven participants, including nine females, mean(SD) age
51.2 (12.1) yrs, with a preoperative BMI of 48.7(9.5)kg/m2
were studied. Weight reduced from a mean (SD) of 133.8 (29.8) kg to
123.8 (28.9) kg post-surgery (p<0.001). The mean (SD) insulin
sensitivity index (ISI-DISST) was
3.07×10−4 (2.18) L.pmol−1.min−1
preoperatively and 2.36
×10−4 (0.78)L.pmol−1.min−1
postoperatively (p=0.37). The mean(SD) clamp ISI was 2.14
×10−2 (1.80) mg.L.kg−1.min−1.pmol−1
and
2.00×10−2.(0.76) mg.L.kg−1.min−1.pmol−1
postoperatively (p=0.86). Correlation between ISI-DISST and
ISI-Clamp preoperatively was r=0.81(95%CI 0.37-0.95) and
post-operatively r=0.47(95%CI 0-0.88). Bland-Altman analysis
demonstrates systematic bias between the two tests, where DISST
underestimated insulin sensitivity compared with the clamp by
0.96×10-2.mg.L.kg−1.min−1.pmol−1
(95%CI -2.24 to 0.32).
Conclusions There was a strong correlation between DISST and the
clamp preoperatively and DISST can be used to estimate insulin sensitivity
in individuals with morbid obesity. After RYGB surgery, DISST had a weaker
correlation with the clamp suggesting the fundamental physiological
determinants of insulin sensitivity being measured by each method change in
different ways with changes in glucose homeostasis following RYGB
surgery.
Key words
dynamic insulin secretion and sensitivity test - Roux-en-Y gastric bypass - obesity - weight loss - Type 2 Diabetes
