The relationship between plasma adiponectin concentration and insulin resistance is altered in smokers.
BACKGROUND
Low plasma adiponectin concentrations in smokers may contribute to the adverse consequences that occur in these individuals.


OBJECTIVE
The objective of the study was to define the relationship among smoking, plasma adiponectin concentrations, insulin resistance, and inflammation.


METHODS
This was a cross-sectional, observational study with a 2 x 2 factorial design and a prospective longitudinal arm.


METHODS
The study was conducted at a general clinical research center.


METHODS
Apparently healthy smokers (n = 30) and nonsmokers (n = 30), subdivided into insulin resistant (IR) (n = 15) and insulin sensitive (IS) (n = 15) subgroups participated in the study.


METHODS
Intervention included pioglitazone administration for 3 months to 12 IR smokers and eight IS smokers.


METHODS
Measures included fasting plasma adiponectin and C-reactive protein (CRP) concentrations and changes in adiponectin after pioglitazone treatment in IR and IS smokers.


RESULTS
Being either a smoker or having insulin resistance was independently associated with lower adiponectin concentrations (P = 0.046 and 0.001, respectively). The difference in mean adiponectin concentration between smokers and nonsmokers did not depend on the insulin resistance status of the subjects. No difference was detected in average CRP concentrations between smokers and nonsmokers (P = 0.18) and between IR and IS subjects (P = 0.13). CRP concentrations were unrelated to adiponectin in smokers (r = -0.05, P = 0.78) and nonsmokers (r = 0.03, P = 0.86). Finally, pioglitazone treatment increased adiponectin concentrations in both IR (P < 0.001) and IS smokers (P = 0.001).


CONCLUSIONS
Plasma adiponectin concentrations are lower in smokers and IR subjects and are unrelated to CRP concentrations. These findings suggest that low levels of adiponectin in smokers may be independent of both insulin resistance and a generalized inflammatory response.
Abbasi
Fahim
F
Department of Medicien, Stanford University School of Medicine, CA 94305, USA.
Farin
Helke M F
HM
Lamendola
Cindy
C
McLaughlin
Tracey
T
Schwartz
Eric A
EA
Reaven
Gerald M
GM
Reaven
Peter D
PD
D052242:Adiponectin / Q000097:blood*; D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000032:analysis; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000032:analysis; D003430:Cross-Sectional Studies; D004341:Drug Evaluation; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D000077205:Pioglitazone; D012907:Smoking / Q000009:adverse effects*; D045162:Thiazolidinediones / Q000494:pharmacology*
D052242:Adiponectin; D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D045162:Thiazolidinediones; D002097:C-Reactive Protein; D000077205:Pioglitazone