A prospective observational study of obesity, body composition, and insulin resistance in 18 women with bipolar disorder and 17 matched control subjects.
OBJECTIVE
Patients with bipolar disorder are at increased risk for diabetes and cardiovascular diseases, possibly because of more severe insulin resistance. The primary purpose of this study was to determine whether insulin resistance is characteristic of bipolar disorder.


METHODS
The Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) was performed in 18 women with DSM-IV bipolar I disorder, and results were compared to those of 17 matched controls. Other risk factors were compared, including blood pressure, blood lipids, and abdominal obesity by computed tomography (CT). Additionally, substrate utilization was measured by indirect calorimetry, and free-living energy expenditure was estimated using wearable activity monitors. All data were collected between February 2006 and December 2007.


RESULTS
Patients with bipolar disorder were no more insulin resistant than controls after accounting for generalized obesity (mean +/- SEM HOMA-IR = 2.7 +/- 0.7 vs. 2.5 +/- 0.7, for patients and controls, respectively; p = .79). Although blood lipid profiles were generally similar in patients and controls, obese patients had higher blood pressure than controls. Obese patients had more mean +/- SEM total abdominal fat (718.1 +/- 35.1 cm² vs. 607.4 +/- 33.6 cm²; p = .04), and tended (p = .06) to have more visceral abdominal fat. Patients oxidized 13% less fat during resting conditions, although their resting metabolic rate was similar to that of controls.


CONCLUSIONS
Women with bipolar I disorder were no more insulin resistant than matched controls after accounting for their level of obesity. However, they were more hypertensive, had higher amounts of abdominal obesity, and had reduced rates of fat oxidation. Therefore, women with bipolar I disorder may be at a heightened risk for future weight gain and concomitant risk for diabetes and cardiovascular disease.
Fleet-Michaliszyn
Sara B
SB
College of Nursing, University of Arizona, Tucson, USA.
Soreca
Isabella
I
Otto
Amy D
AD
Jakicic
John M
JM
Fagiolini
Andrea
A
Kupfer
David J
DJ
Goodpaster
Bret H
BH
D000328:Adult; D001714:Bipolar Disorder / Q000453:epidemiology*; D001823:Body Composition; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000453:epidemiology; D016022:Case-Control Studies; D015897:Comorbidity; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D006949:Hyperlipidemias / Q000453:epidemiology; D006973:Hypertension / Q000453:epidemiology; D024821:Metabolic Syndrome / Q000453:epidemiology*; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology*; D011446:Prospective Studies; D012016:Reference Values; D012307:Risk Factors; D049629:Waist-Hip Ratio