Objective—To examine whether obese cats, compared
with lean cats, have alterations in lipoprotein
metabolism that might lead to a decrease in glucose
metabolism and insulin secretion.
Animals—10 lean and 10 obese adults cats (5
neutered males and 5 neutered females each).
Procedure—Intravenous glucose tolerance tests with
measurements of serum glucose, insulin, and nonesterified
fatty acid (NEFA) concentrations were performed.
Lipoprotein fractions were examined in
serum by isopycnic density gradient ultracentrifugation.
Results—Obese cats had insulin resistance. Plasma
triglyceride and cholesterol concentrations were significantly
increased in obese cats, compared with
lean cats. Very low density lipoprotein (VLDL) concentrations
were increased in obese cats, compared
with lean cats; however, the composition of various
fractions remained unchanged between obese and
lean cats, indicating greater synthesis and catabolism
of VLDL in obese cats. Serum high density lipoprotein
(HDL) cholesterol concentrations were increased in
obese cats, compared with lean cats. Serum NEFA
concentrations were only significantly different
between obese and lean cats when separated by sex;
obese male cats had higher baseline serum NEFA
concentrations and greater NEFA suppression in
response to insulin, compared with lean male cats.
Conclusions and Clinical Relevance—Lipid metabolism
changes in obese cats, compared with lean cats.
The increase in VLDL turnover in obese cats might
contribute to insulin resistance of glucose metabolism,
whereas the increase in serum HDL cholesterol
concentration might reflect a protective effect against
atherosclerosis in obese cats. (Am J Vet Res 2003;64:299–303)
Objective—To determine whether dietary fatty acids
affect indicators of insulin sensitivity, plasma insulin
and lipid concentrations, and lipid accumulation in
muscle cells in lean and obese cats.
Animals—28 neutered adult cats.
Procedure—IV glucose tolerance tests and magnetic
resonance imaging were performed before (lean
phase) and after 21 weeks of ad libitum intake of
either a diet high in omega-3 polyunsaturated fatty
acids (3-PUFAs; n = 14) or high in saturated fatty acids
Results—Compared with the lean phase, ad libitum
food intake resulted in increased weight, body mass
index, girth, and percentage fat in both groups.
Baseline plasma glucose or insulin concentrations and
glucose area under the curve (AUC) were unaffected
by diet. Insulin AUC values for obese and lean cats fed
3-PUFAs did not differ, but values were higher in obese
cats fed SFAs, compared with values for lean cats fed
SFAs and obese cats fed 3-PUFAs. Nineteen cats that
became glucose intolerant when obese had altered
insulin secretion and decreased glucose clearance
when lean. Plasma cholesterol, triglyceride, and nonesterified
fatty acid concentrations were unaffected by
diet. Ad libitum intake of either diet resulted in an
increase in both intra- and extramyocellular lipid.
Obese cats fed SFAs had higher glycosylated hemoglobin
concentration than obese cats fed 3-PUFAs.
Conclusions and Clinical Relevance—In obese cats,
a diet high in 3-PUFAs appeared to improve long-term
glucose control and decrease plasma insulin concentration.
Obesity resulted in intra- and extramyocellular
lipid accumulations (regardless of diet) that likely
modulate insulin sensitivity. (Am J Vet Res