How Does OSAS Severity Affect Glucose Tolerance?

SEATTLE, WA—Severe obstructive sleep apnea syndrome (OSAS) may potentially be associated with pancreatic β-cell functional disorder and glucagon-like peptide-1 (GLP-1) resistance, according to a study conducted at the Division of Behavioral Sleep Medicine, Iwate Medical University School of Medicine, Morioka, Japan, and presented at SLEEP 2015.

Healthy individuals have an increased secretion of GLP-1 with postprandial hyperglycemia followed by a decrease after 30 minutes. However, earlier research has shown that patients with OSAS may have insulin resistance. Tetsuya Kizawa and colleagues aimed to determine the relationship between GLP-1 and the severity of OSAS by studying the time variation of plasma GLP-1 levels in patients with OSAS.

A total of 41 patients with OSAS and HbA1c <6.2% and HOMA-R <2.5 were enrolled.  Patients were stratified into two groups based on their severity of OSAS. Group A (n=19) had AHI≥30 and Group B (n=22) had AHI <30. The team performed glucose tolerance tests and measured plasma glucose, serum insulin, and plasma GLP-1 levels via ELISA before and after 30, 60, 120 minutes of load.

Prior to the glucose load tests, there was a significant difference between Groups A and B in plasma glucose and serum insulin levels. However, there was no similar difference in blood glucose at 30, 60, and 120 minutes. Insulin levels of group A were significantly higher than those of Group B at 30 minutes, but not at 60 or 120 minutes. After 30 minutes, however, plasma GLP-1 levels were significantly higher than pre-load in both groups; no significant difference was found between Group A and B. After 60 minutes, plasma GLP-1 levels in Group B showed a non-significant decline (56.3±0.9pmol/L) but no decline was seen in Group A (10.3 ± 2.6/L). After 120 minutes, plasma GLP-1 levels in Group B dipped significantly lower than Group A (5.5±0.7pmol/L vs. 9.1±1.5pmol/L; P=0.03).

Severe OSAS without insulin resistance and glucose tolerance had prolonged plasma GLP-1 levels after 120 minutes post-glucose load.