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Gastric Bypass Leads to Improvement of Diabetic Neuropathy Independent of Glucose Normalization—Results of a Prospective Cohort Study (DiaSurg 1 Study)

Müller-Stich, Beat P. MD*; Fischer, Lars MD*; Kenngott, Hannes G. MD*; Gondan, Matthias PhD; Senft, Jonas MD*; Clemens, Gabriella MD*; Nickel, Felix MD*; Fleming, Thomas PhD; Nawroth, Peter P. MD; Büchler, Markus W. MD*

doi: 10.1097/SLA.0b013e3182a618b2
Original Articles From the ESA Proceedings

Objective: Surprisingly, 40% to 95% of patients with type 2 diabetes mellitus (T2DM) show early remission of hyperglycemia after obesity surgery. It is unknown to what extent other diabetes-associated comorbidities such as distal peripheral neuropathy (DPN) might be influenced by obesity surgery. This pilot study aimed at providing further evidence for the impact of Roux-en-Y gastric bypass (RYGB) on both glycemic control and DPN in nonseverely obese patients with insulin-dependent T2DM.

Methods: In the present prospective cohort study, 20 patients with long-standing, insulin-dependent T2DM and a body mass index (BMI) between 25 and 35 kg/m2 underwent laparoscopic RYGB. Body mass index, glycosylated hemoglobin (HbA1c), and DPN [quantified by the Neuropathy Symptom Score (NSS) and the Neuropathy Deficit Score (NDS)] were investigated.

Results: Six months after surgery, the preoperative BMI of 32.8 ± 2.1 kg/m2 (mean ± standard deviation) dropped to 25.6 ± 2.5 kg/m2 (P < 0.001). Preoperative HbA1c levels decreased from 8.5 ± 1.2% to 7.1 ± 1.2% (P < 0.001), with 15% of patients having a normalized HbA1c level lower than 6.2%. Of 12 patients with documented DPN, the median NSS was 8 (range, 0–10) preoperatively and 0 (range, 0–9) postoperatively (P = 0.004), with 8 patients scoring an NSS of 0. The median NDS was 6 (range, 2–8) preoperatively and 4 (range, 0–8) postoperatively (P = 0.027), with 1 patient scoring an NDS of 0. All patients had an improvement or normalization in either 1 or both scores.

Conclusions: As expected, BMI and HbA1c levels improved significantly after RYGB. More interestingly, neuropathy scores, such as NSS and NDS, improved significantly early after surgery. Symptomatic neuropathy was completely reversible in 67% of the patients. These findings add further evidence to the fact that RYGB might be a valuable treatment option not only for improving glycemic control but also for reducing diabetes-associated comorbidities, such as DPN. This points to a complex metabolic effect of RYGB that exceeds glucose normalization. However, the results still need to be confirmed in controlled trials.

The effect of gastric bypass on glycemic control and neuropathy was studied in 20 patients with type 2 diabetes. Six months postoperatively HbA1c and neuropathy scores improved significantly. Whereas all 12 patients with documented neuropathy were less symptomatic or free of symptoms, only 15% of patients had normalized HbA1c.

*Department of General, Visceral and Transplantation Surgery, University of Heidelberg, Heidelberg, Germany

Institute of Medical Biometry and Informatics, University of Heidelberg, Heidelberg, Germany

Department of Internal Medicine I and Clinical Chemistry, University of Heidelberg, Heidelberg, Germany.

Reprints: Markus W. Büchler, MD, General, Visceral and Transplantation Surgery, University of Heidelberg, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany. E-mail:

Disclosure: The authors declare no conflicts of interest.

© 2013 by Lippincott Williams & Wilkins.