BACKGROUND/AIMS: Insulin resistance (IR) plays an important role in the 
pathogenesis of diabetes and non-alcoholic fatty liver disease (NAFLD). Current 
methods for insulin resistance detection are cumbersome, or not sensitive enough 
for early detection and follow-up. The BreathID system can continuously analyse 
breath samples in real-time at the point-of-care. Here we determined the 
efficacy of the BreathID using the 13C-Glucose breath test (GBT) for evaluation 
of insulin resistance.
METHODS: Twenty healthy volunteers were orally administered 75 mg of 13C-glucose 
1-13C. An oral glucose tolerance test (OGTT) was performed immediately; followed 
by serum glucose and insulin level determinations using GBT. GBT and OGTT were 
repeated following exercise, which alters insulin resistance levels.
RESULTS: Within-subject correlations of GBT parameters with serum glucose and 
serum insulin levels were high. Before and after exercise, between-subjects 
correlations were high between the relative insulin levels and the % dose 
recoveries at 90 min (PDR 90), and the cumulative PDRs at 60 min (CPDR 60). 
Pairwise correlations were identified between pre-exercise Homeostasis Model 
Assessment (HOMA) IR at 90 min and PDR 90; HOMA B (for beta cell function) 120 
and CPDR 30; HOMA IR 60 and peak time post-exercise; and HOMA B 150 with PDR 
150.
CONCLUSIONS: The non-invasive real-time BreathID GBT reliably assesses changes 
in liver glucose metabolism, and the degree of insulin resistance. It may serve 
as a non-invasive tool for early diagnosis and follow up of patients in 
high-risk groups.