Iron In Insulin Resistance

Iron In Insulin Resistance

Circulating RBP4 concentration might reflect insulin resistance-
associated iron overload.
Fernández-Real JM, Moreno JM, Ricart W
Diabetes 2008 Apr 21.

Objectives:
The mechanisms behind the association between retinol binding protein
4 (RBP4) and insulin resistance are not well understood. An
interaction between iron and vitamin A status, of which RBP4 is a
surrogate, has long been recognized. We hypothesized that iron-
associated insulin resistance could be behind the impaired insulin
action caused by RBP4.
Research Design and Methods:
Serum ferritin and RBP4 concentration, and insulin resistance were
evaluated in a sample of middle-aged men (n=132), and in a
replication, independent study. Serum RBP4 was also studied before and
after iron depletion in patients with type 2 diabetes. Finally, the
effect of iron on RBP4 release was evaluated in vitro in adipose
tissue.
Results:
A positive correlation between circulating RBP4 and log serum ferritin
(r=0.35 and r=0.61, p<0.0001) was observed in both independent
studies. Serum RBP4 concentration was higher in men than women in
parallel to increased ferritin levels. On multiple regression analyses
to predict serum RBP4, log serum ferritin contributed significantly to
RBP4 variance after controlling for BMI, age and HOMA value. Serum
RBP4 concentration decreased after iron depletion type 2 diabetic
patients (percent mean differences -13.7 (-25.4 to -2.04, p=0.024).
The iron donor lactoferrin led to increased dose-dependent adipose
tissue release of RBP4 (2.4 fold, p=0.005) and increased RBP4
expression while apotransferrin and deferoxamine led to decreased RBP4
release.
Conclusions:
The relationship between circulating RBP4 and iron stores, both cross-
sectional and after iron depletion, and in vitro findings suggest that
iron could play a role in the RBP4-insulin resistance relationship.
Diabetes [Diabetes]
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