Objective: Because higher iron level is associated with increased risk of type 2 diabetes and bariatric surgery is known to alter iron homeostasis, we examined the effects of tissue iron stores on glycemic outcome after bariatric surgery.

Research Design and Methods: We performed a retrospective analysis of glycemia outcomes after Roux-en Y gastric bypass (RYGB) or vertical sleeve gastrectomy (VSG) in individuals with elevated hemoglobin A1c (HbA1c) as a function of serum ferritin before and after surgery, using two large and independent electronic health databases from the Carolinas Collaborative and University of Michigan.

Results: Improvement of HbA1c, weight, and alanine aminotransferase (ALT) was comparable between the two procedures 6-12 months after surgery. For gastric bypass procedures, however, the improvement in HbA1c and the chance of normalizing HbA1c were inversely proportional to preoperative ferritin, while no such relationship existed for gastrectomy. The improvement in ALT was correlated with the decrease in serum ferritin after surgery for both surgery types. Changes in hemoglobin were also related to preoperative ferritin.

Conclusion: Preoperative iron stores may modulate glycemic improvement after bariatric surgery differentially depending on procedure type. This has implications regarding the operation of choice in certain patient populations.


J. Tong: None. R. Alvarez: None. G.B. Russell: None. A.N. Khouri: None. R.J. Seeley: Consultant; Self; Ionis Pharmaceuticals, Inc., Kintai, Kintai, Novo Nordisk A/S, Sanofi, Scohia Pharma Inc. Research Support; Self; AstraZeneca, Novo Nordisk A/S, Pfizer Inc. Stock/Shareholder; Self; Redesign Health. D.A. McClain: None.


National Institutes of Health (R01DK097550)

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