Background: Hypoglycaemia after an oral glucose tolerance test (OGTT) can occur in up to 33 % of subjects after laparoscopic sleeve gastrectomy (LSG). The underlying pathophysiology is not well understood. We aimed to compare the anthropometric and metabolic characteristics of subjects with post-OGTT hypoglycaemia (HYPO) to subjects with post-OGTT euglycaemia (EU) 6 months after LSG.
Methods: Eighteen morbidly obese patients with normal glucose tolerance (NGT) were evaluated with an OGTT before and 6 months after LSG. Serum glucose and insulin were measured before and every 30 min after glucose ingestion up to 120'. The patients were categorized as HYPO or EU based on lowest glucose levels 90' to 120' post-OGTT 6 months after LSG (hypoglycaemia defined as glucose levels <60 mg/dl). OGTT derived indices of insulin secretion; insulin sensitivity and beta cell function were also evaluated.
Results: Eight patients (44.4 %) were categorized as HYPO. Preoperatively, subjects with HYPO had lower BMI (p = 0.02) compared to that with EU. Postoperatively, subjects with HYPO had lower BMI (p = 0.01), lower weight (p = 0.01), and higher percentage of total weight loss (%TWL) (p = 0.03) compared to that with EU. The beta cell function index was higher in the HYPO group postoperatively compared to EU (p = 0.02)-especially during the latter portion of the OGTT. No difference was detected in insulin secretion and insulin sensitivity indices between the two groups preoperatively or postoperatively.
Conclusions: Subjects with NGT who developed HYPO 6 months after LSG are leaner, with higher TWL% and higher beta cell function at the latter portion of the OGTT compared to those with EU.
Keywords: Bariatric surgery; Hypoglycaemia; Oral glucose tolerance test; Sleeve gastrectomy.