Abstract
AIMS/INTRODUCTION: Adiponectin has been proposed to have an essential role in the regulation of insulin sensitivity and metabolism, but previous studies on levels of adiponectin in prediabetes remain inconsistent. The present study aimed to assess the differences of adiponectin levels between prediabetes patients and healthy controls by carrying out a meta-analysis. MATERIALS AND METHODS: We carried out a systematic literature search of PubMed, EMBASE, and other databases for case-control studies and cohort studies measuring adiponectin levels in serum or plasma from prediabetes patients and healthy controls. The pooled weighted mean difference (WMD) and 95% confidence interval (CI) were used to estimate the association between adiponectin levels and prediabetes. RESULTS: Three cohort studies and 15 case-control studies with a total of 41,841 participants were included in the meta-analysis. The results showed that circulating adiponectin levels in prediabetes patients were significantly lower than that of healthy controls (WMD -1.694 μg/mL; 95% CI -2.151, -1.237; P < 0.001). Subgroup analysis showed more significant differences between prediabetes patients and healthy controls when the ratio of the homeostatic model assessment of insulin resistance was >2.12 (WMD -2.95 μg/mL; 95% CI -4.103, -1.806; P < 0.001) and average age was >60 years (WMD -2.20 μg/mL; 95% CI -3.207, -1.201; P < 0.001). Additionally, WMD in adiponectin showed a trend of direct correlation in subgroups of homeostatic model assessment of insulin resistance ratio, body mass index and age. CONCLUSIONS: The present meta-analysis supports adiponectin levels in prediabetes patients being lower than that of healthy controls,indicating that the level of circulating adiponectin decreases before the onset of diabetes.