Bariatric Surgery in T1D Causes Sustained Weight Loss, Improves Comorbidities

Despite achieving durable weight loss and reducing required insulin, bariatric surgery in adults with type 1 diabetes (T1D) also emphasized the need for close perioperative diabetes management due to variable glycemic outcomes.¹

Presented at the American Association of Clinical Endocrinology (AACE) Annual Meeting 2026 in Las Vegas, Nevada, by Lena Ayari, MD, from the department of endocrinology at Mayo Clinic Rochester, this retrospective cohort study aimed to evaluate the long-term outcomes of bariatric surgery in patients with T1D, including mortality, diabetic ketoacidosis (DKA), severe hypoglycemia, insulin regimen changes, and weight trajectory.¹

Bariatric surgery remains a cornerstone of treatment for obesity and metabolic dysfunction in type 2 diabetes (T2D); however, evidence is limited regarding its efficacy and safety in T1D. Previous studies examining the operation’s effectiveness in patients with T1D have often noted a modest or insignificant reduction in mean glycosylated hemoglobin, which experts have thus far been unable to sufficiently explain.²

“Existing studies are small and raise concerns about postoperative complications such as diabetic ketoacidosis (DKA) and severe hypoglycemia,” Ayari and colleagues wrote. “Comprehensive long-term data are needed to better define risks, benefits, and ongoing care needs in T1D patients undergoing bariatric surgery.”¹

To address this, Ayari and colleagues collected data on patients with T1D undergoing surgery, including demographics and procedure type, insulin regimen changes, DKA and severe hypoglycemia events, serial body mass index (BMI) and HbA1c, and comorbidities such as hypertension and obstructive sleep apnea. The team performed descriptive analyses to characterize outcomes, while longitudinal trends of weight, insulin use, and healthcare utilization were evaluated via within-subject comparisons over time.¹

All patients lost a significant amount of weight early in the study, with mean BMI decreasing from 39.3 kg/m2 preoperatively to the low-mid 30s at 6-12 months. Weight loss was also largely maintained through long-term follow-up – some regained weight by years 2-5, but all remained below baseline.¹

Regarding glycemic outcomes, the majority of patients saw early improvement in HbA1c, although several underwent deterioration or return to preoperative A1c levels despite sustained weight loss. Insulin requirement, however, decreased in nearly all patients, taking the form of reduced injection doses, lower daily insulin needs on pump therapy, and reductions in bolus insulin needs. In 1 patient, investigators saw a transition from high-dose NPH to lower-dose basal regimens.¹

Only 1 patient had an episode of DKA, which occurred early in the postoperative period as a result of missed insulin doses. Several patients exhibited fasting hypoglycemia, although severe hypoglycemia was uncommon and there were no recurrent DKA events after the initial postoperative period. Patients also saw frequent improvements in hypertension and obstructive sleep apnea, with multiple discontinuing CPAP or antihypertensives. Lipids and renal functions were largely stable.¹

Ultimately, Ayari and colleagues determined that bariatric surgery in T1D resulted in durable weight loss, improvement in comorbidities, and reduced insulin requirements. Early HbA1c improvement was common among the included patients, although long-term glycemic control varied. Additionally, DKA and fasting hypoglycemia, among other signals of postoperative metabolic instability, emphasize the need for close management following the procedure.¹

“These findings demonstrate both the potential benefits and important limitations of bariatric surgery in T1D and support the need for larger, long-term studies to guide patient selection, risk mitigation, and postoperative care strategies,” Ayari and colleagues wrote.¹

References

1. Ayari L, Rizvi S, Kudva Y. Long-Term Clinical Outcomes Following Bariatric Surgery in Adults With Type 1 Diabetes. Abstract presented at the American Association of Clinical Endocrinology Annual Meeting 2026, Las Vegas, NV. April 22-24, 2026.

2. Korakas E, Kountouri A, Raptis A, Kokkinos A, Lambadiari V. Bariatric Surgery and Type 1 Diabetes: Unanswered Questions. Front Endocrinol (Lausanne). 2020;11:525909. Published 2020 Sep 18. doi:10.3389/fendo.2020.525909