Circulating apelin is increased in patients with type 1 or type 2 diabetes and is associated with better glycaemic control.

ABSTRACT

CONTEXT Apelin is an adipokine expressed in several tissues and it appears to be involved in energy metabolism. OBJECTIVE: The aim of this study was to determine serum apelin levels in a large cohort of patients with type 1 and type 2 diabetes and control subjects and to correlate the results with glycaemic control. DESIGN AND PARTICIPANTS: One hundred and thirty patients with type 1 diabetes, 98 patients with type 2 diabetes and 162 controls were enrolled in the study. Apelin levels were measured by enzyme-linked immunosorbent assay. RESULTS: Serum apelin levels were significantly higher in type 1 and type 2 diabetic patients than in controls (P < 0·0001). Serum apelin levels were higher in type 1 than in type 2 diabetic patients (P = 0·02). In multivariate analysis, serum apelin levels were higher in patients with type 1 diabetes and in patients with type 2 diabetes versus controls. We found a negative correlation between glycosylated haemoglobin and serum apelin levels in all diabetic patients (r = -0·17, P = 0·008) and in patients with type 2 diabetes (r = -0·24 P = 0·01). No correlation was found in type 1 diabetic patients. CONCLUSION: Our study showed that apelin concentrations were increased in diabetic patients. This rise, which was greater in type 1 than in type 2 diabetic patients, suggests that obesity is not the main determinant of plasma apelin levels. The negative correlation with glycosylated haemoglobin in patients with type 2 diabetes could indicate that apelin plays a role in glycaemic balance and even insulin sensitivity.