Changes in the Distribution of Adiponectin Isoforms within Total Adiponectin in Japanese Subjects with Abdominal Obesity and their Relation to Insulin Resistance and Metabolic Syndrome

Changes in the distribution of adiponectin isoforms, especially middle-and low-molecular-weight (MMW, LMW) adiponectin (Ad), within total adiponectin (T-Ad) in subjects with abdominal obesity (AO) and how these changes might be related to insulin resistance (IR) and metabolic syndrome (MS) are not yet well-known. In the present study, we examined these changes and their relations to IR and MS. We compared the serum Ad-related parameters in a group of 283 subjects with AO and 485 subjects without AO (1st cohort). In addition, we also examined the associations between the Ad-related parameters and the HOMA-IR in a 2nd cohort, consisting of subjects of the 1st cohort except for those with diabetes. In the 1st cohort, in the subjects with AO as compared with those without AO, the distribution of Ad isoforms within T-Ad changed, with a lower percentage of high-molecular-weight (HMW)-Ad and higher percentage of MMW-Ad and LMW-Ad, resulting in higher MMW-Ad/HMW-Ad and LMW-Ad/HMW-Ad ratios (P values <0.01 for all). Among these changes, the increased LMW-Ad/T-Ad and LMW-Ad/ HMW-Ad ratios tended to be positively associated with MS (P = 0.07). In the 2nd cohort, similar to the case for MS, these ratios were also significantly positively correlated with the HOMA-IR (P values <0.01 for all), independent of the BMI. The current investigation demonstrated changes in the distribution of the Ad isoforms, especially increase in the LMW-Ad/T-Ad and LMW-Ad/HMW-Ad ratios, in subjects with AO, and significant BMI-independent association of these changes with the severity of IR and risk of development of MS.