Role of hypoadiponectinemia in the metabolic syndrome and its association with post-glucose challenge hyper-free fatty acidemia: a study in prediabetic Japanese males

Abstract

We investigated the role of hypoadiponectinemia in the metabolic syndrome (MS), as well as its association with post-glucose challenge hyper-free fatty acidemia in the clinical setting. The study subjects comprised 177 corporate employees shown to have a fasting plasma glucose (FPG) level of 125 mg/dL or less in a 75 g OGTT in the corporation's healthcare center. When divided into those who met the Japanese criteria for the metabolic syndrome (MS group; n = 45) and those who did not (Non-MS group; n = 132), the MS group was shown to have significantly lower adiponectin levels than the Non-MS group, and tended to show higher high-sensitivity C-reactive protein (CRP) values than the Non-MS group, while not achieving statistical significance. The MS group showed higher baseline glucose levels; higher baseline, 30-, 60-, and 120-min post-challenge insulin levels; higher 30-, 60-, and 120-min post-challenge free fatty acid levels than the Non-MS group. Additionally, there was a significant, negative correlation between adiponectin levels, area under the free fatty acid curve, and area under the insulin curve at OGTT (r = -0.24, p < 0.01; r = -0.21, p < 0.01, respectively). When the patients were divided by adiponectin level into four groups to examine the number of risk factors for MS detected per patient and the incidence of MS, the lower the adiponectin level, the more risk factors were found per patient, with 68% of patients with an adiponectin level of less than 4 microg/mL found to have MS. In those with an adiponectin level of less than 4 microg/mL, BMI values, uric acid levels, HOMA-R values, and the number of risk factors for MS involved per patient were shown to be higher than in those with an adiponectin level of 4 microg/mL or greater. Furthermore, the following risk factors for MS were more frequently found in those with an adiponectin level of less than 4 microg/mL than in those with an adiponectin level of 4 microg/mL or greater: VFA > or = 100 cm2 (OR 12.8, p < 0.001); TG > or = 150 mg/dL (OR 3.2, p < 0.05); HDLC < 40 mg/dL (OR 1.9, p = 0.29); BP > or = 130/85 mmHg (OR 2.2, p = 0.15); and FPG > or = 110 mg/dL (OR 1.9, p = 0.29). Again, the incidence of MS (OR 7.6, p < 0.001) by the ATPIII criteria, as well as that by the Japanese criteria (OR 8.6, p < 0.001), was found to be higher in those with an adiponectin level of less than 4 microg/mL than in those with an adiponectin level of 4 microg/mL or greater. Our study results suggest that adiponectin is closely associated with the multiple risk factors that go to make up the MS, suggesting a role for hypoadiponectinemia as a surrogate marker for the MS and further appear to suggest that post-challenge hyper-free fatty acidemia may account in part for hypoadiponectinemia in the MS.