SLEEP 2011 Abstract Supplement

A. Basic Science XII. Instrumentation and Methodology
with 10h nighttime sleep (TIB 22:00-08:00), subjects were given a
5h nap (TIB 15:00-20:00), and underwent 5 days of night work with
daytime sleep (TIB 10:00-20:00). Subjects then had a recovery period,
which began with a 5h nap (TIB 10:00-15:00) and was followed by 10h
nighttime sleep (TIB 22:00-08:00). On the second baseline day and after
recovery, 24h glucose profiles were measured in interstitial fluid (sampled
every 5 minutes), using the subcutaneous glucose monitor inserted
into an area of the lower back accommodating subcutaneous placement
while minimizing catheter movement due to pressure from clothing. Additionally,
blood was taken at 2h intervals by intravenous catheter, spun,
aliquoted, stored at −80°C, and assayed for glucose by Biovision Glucose
Assay. Subjects were mobile during scheduled wakefulness; meals
provided were identical for the two measurement days to control for
carbohydrate intake.
Results: The intravenous glucose levels were entered into Medtronic
glucose software to calibrate the interstitial glucose profiles. These profiles
were analyzed using mixed-effects ANOVA to compare baseline
glucose traces to post-recovery traces. Over all subjects, the baseline
glucose trace explained 4.8% of the variance in the post-recovery trace.
Analyzing only the two subjects with the least noisy data, the baseline
trace explained 44.4% of the variance in the post-recovery trace.
Conclusion: Although in specific cases, 24h subcutaneous glucose profiles
were replicable within subjects, this was not true in general. Postrecovery
glucose profiles may have differed from baseline profiles due
to the intervening night work schedule. Even so, the data seemed particularly
noisy, potentially because subjects were ambulatory, which may
have resulted in movement artifact. This could be mitigated by keeping
subjects stationary and/or changing catheter placement location.
Support (If Any): FMCSA award DTMC75-07-D-00006
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SLEEP, Volume 34, Abstract Supplement, 2011