390-P: Changes in Glycaemic Variability after RYGB: A One-Year Prospective Study with Comparison to Patients with Post-bariatric Hypoglycaemia

Some patients suffer disabling hypoglycaemia after RYGB, typically post prandially: Post Bariatric Hypoglycaemia (PBH). We hypothesised that these patients have increased glycaemic variability (GV), as assessed by continuous glucose monitoring (CGM). Method: Prospective study of 6 patients undergoing RYGB with mixed meal tests (MMT) and CGM at baseline (BL), at 1 month and at 12 months. This cohort was compared to 15 patients with hypoglycaemia. Results: RYGB leads to improvement in postprandial glucose tolerance at 120 minutes, preceded by an early peak of glucose and insulin at 30 minutes (Figure 1). Compared to pre-surgery, hypoglycaemic patients have significantly elevated peak glucose and insulin levels at 30 minutes followed by hypoglycaemia at 120 minutes. GV increases post RYGB: mean amplitude of glycaemic excursions (MAGE) median (95% CI) at BL 3.1 (2.3-6.8); 1 m 2.8 (2.2-4.2); 12 m 4.5 (3.4-5.5). PBH patients exhibit similar GV: MAGE 4.4 (3.7-6.5). The %time in range (TIR) glucose <3.9 increases post-surgery (BL 0 (0-3.8); 1 m 1.8 (0.5-4.1); 12 m 8.0 (0-25.8) but patients with PBH exhibit similar %TIR<3.9: 6.8 (3.5-11.9). Conclusion: PBH patients exhibit exaggerated early glucose and insulin secretion to MMT. ‘Real-world’ CGM demonstrates that GV and time in hypoglycaemia is not significantly different between RYGB without PBH and patients with PBH. All patients post RYGB are at risk of hypos. Disclosure G. Tharakan: None. I.I. Ilesanmi: None. P. Behary: None. K. Alexiadou: None. C.S. Doyle: None. H. Chahal: None. S. Purkayastha: None. A. Miras: None. N. Oliver: Advisory Panel; Self; Roche Diabetes Care. Research Support; Self; Dexcom, Inc., Roche Diabetes Care. Speaker's Bureau; Self; Dexcom, Inc., Sanofi. A. Ahmed: None. S. Bloom: None. T.M. Tan: Other Relationship; Self; Novo Nordisk A/S. Funding Medical Research Council UK