Endocrine Abstracts

Background: Literature suggests that whole glucose excursion, rather than plasma glucose concentration at a point, provides more information about glucose tolerance. The glucose area under the curve (AUC) is an index of whole glucose excursion after glucose load. We sought to investigate changes in insulin and glucose homeostasis, including the glucose AUC, 5 years after bariatric surgery.

Method: A non-randomised prospective study of 18 participants with T2DM undergoing bariatric surgery [12 females, mean age 50.4±6.4 years, mean body mass index 55.3±14.1 kg/m², median duration of diabetes 29 months]. Serial measurements of glucose, insulin and C-peptide were performed during the 75-g oral glucose tolerance test pre-operatively and 5 years post-operatively. The glucose AUC were examined at 30, 60 and 120 minutes.

Results: Significant reduction (baseline vs 5 years) in 2-hr plasma glucose (2 hr-PG) [13.4 (10.1–16.4) vs 8.4 (6.0–12.1) mmol/L, p=0.007]; HbA1c [7.5±1.7 vs 6.4±1.4%, p=0.001]; fasting C-peptide [1.3±0.5 vs 0.7±0.5 nmol/L, p=0.004]; 2-hr C-peptide [3.2±1.6 vs 1.9±1.4 nmol/L, p=0.033]; and improvement in HOMA%S [log transformed (1.5±0.2 vs 1.8±0.4, p=0.02)] were observed. Fasting plasma glucose (FPG) showed non-significant reduction at 5 years [7.6 (5.8–9.4) vs 6.5 (5.6–9.1) mmol/L, p=0.136]. There were no changes in the median glucose AUC_0-30 4.5 (3.9–6.1) vs 4.5 (3.4–6.5), AUC_0-60 10.9 (9.4–15.0) vs 10.4 (8.5–15.2) and AUC_0-120 18.4 (14.2–22.9) vs 18.7 (11.7–21.5), baseline vs 5 years, respectively.

Conclusion: The traditional glycaemic markers (2 hr-PG and HbA1c) suggest improvement in glucose homeostasis 5 years after bariatric surgery. However, the glucose AUC measures suggest otherwise.