Glycemic variability and entero-pancreatic hormones signatures after different bariatric surgery procedures: a cross-sectional study

Bariatric surgery changes food handling and entero-pancreatic endocrine dynamics. We aimed at understanding the influence of anatomical reorganization of the gastrointestinal tract induced by metabolic and bariatric surgery (BS) on glycemic variability and the extent to which glycemic variability reflects the underlying entero-pancreatic hormone dynamics. We performed a cross-sectional study on glycemic variability after four different BS procedures in comparison with non-operated matched controls (n = 8). The surgical groups were the classic Roux-en-Y gastric bypass (C-RYGB, n = 8), a modified long biliopancreatic limb RYGB (M-RYGB, n = 7), a single-anastomosis duodeno-ileal bypass with sleeve gastrectomy (SADI-S, n = 8) and a biliopancreatic diversion with duodenal switch (BPD-DS, n = 7). Participants completed 14 days of intermittently scanned continuous glucose monitoring (isCGM). The surgical groups also underwent a mixed-meal test with hormone profiling. Our primary outcome was the mean absolute glucose change (MAG change) in the operated vs non-operated individuals. Additionally, we developed, validated and herein release an automated tool, Gluc4all, for personalized and automated continuous glucose monitoring data analysis, particularly relevant when evaluating the glycemic profile of individuals without diabetes. All surgical interventions were associated with an increase in the magnitude of postprandial glucose excursions, in anatomy-specific patterns (MAG change was 2.0-fold higher after C-RYGB and M-RYGB and 1.6-fold higher after SADI-S and BPD-DS than in non-operated controls). These isCGM findings matched the postprandial glucose, glucose-dependent insulinotropic peptide (GIP), glucagon-like peptide-1 (GLP-1) and insulin profiles documented in the meal test. Overall, we show that BS interventions are associated with higher glycemic variability. Moreover, depending on the type of gastrointestinal anatomical reconstruction, BS yields procedure specific glycemic variability patterns. This might be due to faster glucose absorption, impaired amino acid absorption, and/or altered entero-pancreatic hormone profiles, including GLP-1 and insulin secretion.