January 24, 2009 -- In a study that addressed the issue of insulin sensitivity with respect to sleep
disordered breathing (SDB), Naresh Punjabi, M.D., Ph.D. sought to examine the
relationship between SDB and insulin resistance using the best tools at his
disposal to do so.
The results definitively link SDB to pre-diabetic
changes in insulin production and glucose metabolism. It was published in the
first issue for February of the American Journal of Respiratory and Critical
Care Medicine, published by the American Thoracic Society.
“In the past
researchers have used body mass index, or BMI, as a proxy measure for body fat,
but we know this to be a variable and crude tool to assess the true percentage
of body fat,” said Dr. Punjabi. “In addition, previous studies have used
surrogate measurements to assess the body's response to insulin without
investigating the interaction that occurs between reduced insulin sensitivity
and increased insulin production in the body.”
To address the
shortcomings of previous studies, Dr. Punjabi and colleagues used two tools in
their investigation into the link between SDB and insulin resistance:
dual-energy x-ray absorptiometry (DEXA), a highly precise technique for
assessing body fat, and frequently sampled intravenous glucose tolerance test
(FSIVGTT), which provides a detailed picture of the subject’s insulin
sensitivity over time, rather than a simple snapshot at a specific
moment.
They recruited 118 subjects, 39 who had no SDB, and 79 who were
newly diagnosed with SDB but who had not been treated. Each subject underwent a
sleep study to assess their level of SDB, and then underwent a FSIVGGT to
determine their glucose metabolism and insulin sensitivity/production the
following day.
“Our major finding was that, as we suspected, SDB was
strongly associated with a decrease in the three major metabolic pathways that
the body uses to metabolize glucose— insulin sensitivity, glucose effectiveness,
and pancreatic cell function— independent of adiposity,” said Dr. Punjabi. “What
our research tells us is that SDB is characterized by multiple physiological
deficits that increase the predisposition for type 2 diabetes mellitus.”
A news release courtesy of American Thoracic Society, a leading medical association dedicated to advancing pulmonary, critical care and
sleep medicine.
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