Evaluation of serum zonulin level in prediabetic patients

This study aimed to investigate the relationship between lipopolysaccharide (LPS) and zonulin levels and also to show the effect of acute hyperglycemic stress induced by oral glucose tolerance testing (OGTT) on zonulin levels in pre-diabetic patients.

Four groups were constituted according to the criteria of the American Diabetes Association (ADA), based on OGTT results: control group (n:40); prediabetic group (n:56), divided into two subgroups: impaired fasting glucose group (IFG) (n:36), and impaired glucose tolerance (IGT) + IFG group (n:20) and type-2 diabetes mellitus (T2DM) group (n:45).

Zonulin and LPS did not significantly differ between the prediabetes and control groups, but were significantly higher in the T2DM group compared to both the prediabetic and the control group (P<0.001). After OGTT, zonulin and LPS were significantly higher in the prediabetes group compared to the control group (P<0.01 and P<0.05, respectively), and significantly lower in the IFG and IFG+IGT groups compared to the T2DM group (P<0.001, P<0.001 and P<0.001, P<0.001, respectively). A positive correlation was detected between fasting zonulin and 2-hour zonulin (r=0.727, P<0.001) and between fasting LPS (r=0.555, P<0.001) and 2-hour LPS (r=0.567, P<0.001) in the prediabetic group. Increased zonulin and LPS levels and the positive correlation between these levels during the prediabetic period although non significant suggests onset of intestinal permeability.

During acute hyperglycemia in prediabetic patients, up-regulation of zonulin and LPS may affect intestinal function. The intestines may play a key role in up-regulation of glucose and the pathogenesis of diabetes.