Relative insulin resistance occurs in obese subjects, perhaps
because of down regulation of insulin receptors due to
hyperinsulinaemia.
Obese subjects have a considerably
increased risk of developing Type 2 diabetes. Fat distribution is
relevant to the development of diabetes, so that those who are
“apple shaped” (android obesity, waist-hip ratio 0·9) are more
prone to Type 2 diabetes than
those who are “pear shaped”
(gynoid obesity, waist-hip ratio 0·7).
The importance of leptin in the evolution of lifestyle related obesity is unclear.
Leptin
is a single chain peptide produced by
adipose tissue and its receptors are expressed widely
throughout the brain and peripheral tissues; when injected into
leptin deficient rodents it causes profound hypophagia and
weight loss. Plasma leptin levels rise in parallel with body fat
content.
Although very rare cases of morbid obesity due to
leptin deficiency have been reported, and are shown to
respond to leptin injections, there is in general an absence of
measurable biological responses to leptin, which at present has
no role in the management of obesity.
No comments:
Post a Comment