Diabetes Risk Falls as Adiponectin Levels Rise
Reported July 07, 2009
HOUSTON, July 7 — Higher levels of the fat-derived hormone adiponectin may reduce the risk of type 2 diabetes, data from a meta-analysis suggest.
Every 1-log µg/mL increase in adiponectin was associated with almost a 30% reduction in the risk of type 2 diabetes. The association remained consistent across all ethnic groups — by type of adiponectin assay, method of diabetes ascertainment, duration of follow-up, or proportion of women in a study.
High-risk populations derived the most benefit from higher levels of the hormone, Rob van Dam, PhD, of the Harvard School of Public Health, and colleagues reported in the July 8 Journal of the American Medical Association.
“Although these epidemiologic studies cannot establish causality, the consistency of the association across diverse populations, the dose-response relationship, and the supportive findings in mechanistic studies indicate that adiponectin is a promising target for the reduction of risk of type 2 diabetes,” the authors said.
Secreted by adipocytes, adiponectin has anti-inflammatory and insulin-sensitizing properties.
Preclinical studies and metabolic studies in humans have suggested that adiponectin might decrease the risk of type 2 diabetes. Proposed mechanisms have included suppression of hepatic gluconeogenesis and stimulation of fatty acid oxidation, glucose uptake, and insulin secretion.
Dr. van Dam and colleagues sought to determine the consistency of the association between adiponectin levels and risk of type 2 diabetes in prospective cohort studies and to evaluate the results by means of a meta-analysis.
Investigators conducted a literature review and identified 13 prospective studies with a total of 14,598 participants and 2,623 cases of type 2 diabetes. Six studies primarily included whites, whereas the remainder included a mix of racial/ethnic groups, or focused on specific nonwhite populations.
Type 2 diabetes was diagnosed by oral glucose tolerance tests in seven studies and by self-reported information or a combination of blood glucose assessment and self-reports.
The analysis revealed an inverse association between adiponectin levels and the risk of type 2 diabetes. The relative risk was 0.72 per 1-log µg/mL increase in adiponectin levels.
Patients at high risk for type 2 diabetes benefited the most from higher levels of adiponectin. The absolute risk difference per 1-log µg/mL increment of adiponectin level was 3.9 per 1,000 person-years in older patients and 30.8 in patients with impaired glucose tolerance.
“Currently, adiponectin is among the strongest and most consistent biochemical predictors of type 2 diabetes,” the authors concluded.
However, they noted that epidemiological studies cannot establish causality or exclude the possibility that adiponectin is a surrogate marker.
The authors also acknowledged that they could not exclude the possibility of confounding by clinical or demographic variables. In addition, they could not rule out possible misclassification of type 2 diabetes.
Primary source: Journal of the American Medical Association