A study published in the July 9 issue of JAMA finds
an association between higher than normal levels of the protein
fetuin-A and an increased risk of developing diabetes. Fetuin-A is one
of several blood proteins that is produced in the liver and secreted
into the blood stream, and it is involved with the transport of various
substances in the blood stream.
Joachim H. Ix, M.D., M.A.S. (University of California, San
Diego, and San Diego Veterans Affairs Healthcare System) and
colleagues, authors of the JAMA study, write that,
“Type 2 diabetes mellitus has become a global epidemic and the
increased prevalence of obesity is a major contributing factor.
However, diabetes does not develop in all obese individuals and there
is a strong genetic contribution to risk. Despite significant recent
advances, mechanisms responsible for individual differences in clinical
phenotype remain largely unknown.” Though there has been no evidence to
link the protein to type 2 diabetes, other studies have demonstrated an
association between higher fetuin-A levels and resistance to insulin.
To examine the potential relationship between higher fetuin-A levels
and the occurrence of diabetes in older persons, Ix and colleagues
studied 406 people, age 70 to 79 years, who did not have diabetes.
Their fetuin-A levels were measured at the beginning of the study and
again after six years of follow-up. The rate of diabetes occurrence
was 10.1 cases/1,000 person-years, as 135 participants
developed the disease.
The researchers found that as fetuin-A levels increased, the incidence
of diabetes also increased. The incidence rate for the third of the
sample with the highest fetuin-A levels was 13.3 cases/1,000
person-years, while the rate for the third with the lowest levels of
the protein was 6.5 cases/1,000 person-years – the former more than two
times the latter. The association held after the researchers
statistically controlled for sex, race, obesity status, physical
activity, inflammatory biomarkers, and other known measures of insulin
resistance. However, there was a slight weakening in the association
when controlling for fat accumulation around the abdomen (visceral
adiposity).
“Future studies should evaluate whether the results may generalize to
middle-aged individuals in whom the [diabetes] incidence rate is
highest. If confirmed in future studies, fetuin-A may ultimately prove
useful as a target for therapeutics, and its study may provide novel
insights to glucose metabolism in humans,” conclude the authors.
Fetuin-A and Incident Diabetes Mellitus in Older Persons
Joachim H. Ix; Christina L. Wassel; Alka M. Kanaya; Eric Vittinghoff;
Karen C. Johnson; Annemarie Koster; Jane A. Cauley; Tamara B. Harris;
Steven R. Cummings; Michael G. Shlipak; for the Health ABC Study
JAMA (2008). 300[2]: pp. 182
– 188.
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: Peter M Crosta