Circulating adiponectin levels, body composition and obesity-related variables in Prader-Willi syndrome: comparison with obese subjects

Abstract

Background: People with obesity and/or the metabolic syndrome have an increased risk for developing diabetes and cardiovascular disease and may have low adiponectin levels. The obesity associated with Prader-Willi syndrome (PWS) would be expected to have similar complications. However, it was recently reported that, despite their adiposity, people with PWS have reduced visceral fat and are less likely to develop diabetes mellitus or the metabolic syndrome compared with people with simple obesity.

Objective: To determine if plasma adiponectin levels and other variables relevant to diabetes and cardiovascular risk are different in a cohort of PWS subjects with known genetic subtypes compared with age-, sex- and weight-matched control subjects.

Results: Fasting plasma glucose, C-peptide, triglycerides, leptin and cholesterol levels were similar in PWS and obese subjects. Our 20 PWS subjects (mean age = 27.7 years) had higher percent body fat (54.1 vs 48.5%) determined by DEXA measurements and lower percent lean mass (45.9 vs 51.5%) compared with 14 obese controls (mean age = 26.9 year). Plasma adiponectin levels were significantly higher in PWS (15.5 +/- 8.2 microg/ml) than in obese controls (7.5 +/- 2.7 microg/ml). A significant positive correlation was found with insulin sensitivity in PWS subjects (r = 0.75, P = 0.0003) but not in obese controls (r = 0.36, P = 0.20).

Discussion: Our study confirmed an earlier observation of higher adiponectin levels in PWS subjects and less insulin resistance proportionate to their obesity status than found in subjects with simple obesity. Furthermore, no differences were seen in PWS subjects with the chromosome 15 deletion or maternal disomy 15. The reported excessive visceral adiposity in subjects with simple obesity compared with PWS may be associated with decreased production and lower circulating levels of adiponectin.

Figure 1

Correlation of adiponectin with measures of insulin resistance and sensitivity. (a) Pearson product moment correlation coefficient for fasting plasma adiponectin and insulin sensitivity as calculated by the QUICKI formula (Katz et al.). (b) Pearson product moment correlation coefficient for fasting plasma adiponectin and insulin resistance as calculated by the HOMA formula (Matthews et al.).

Figure 2

Correlation of fasting plasma adiponectin with measures of body composition. (a) Pearson product moment correlation coefficient for fasting plasma adiponectin and waist-to-hip circumference ratio. (b) Pearson product moment correlation coefficient for fasting plasma adiponectin and percentage of body fat.