How Bariatric Surgery Can Affect Diabetes Complications

Bariatric surgery may be an effective approach to manage 2 major diabetes complications in individuals with class II/III obesity: peripheral neuropathy (PN) and cardiovascular autonomic neuropathy (CAN).

A prospective cohort study published in Diabetologia found that bariatric surgery was effective at improving several metabolic risk factors, with the exception of blood pressure (BP) and total cholesterol. There was also a significant mean (SD) weight loss of 31.0 (18.4) kg observed at the 2-year follow-up after bariatric surgery, and fewer individuals were found to be taking antihypertensive medications after the surgery.

Two years following bariatric surgery, one of the primary PN outcomes, intraepidermal nerve fiber density (IENFD) in the proximal thigh, showed a mean improvement of 3.4 (7.8) fibers/mm (P < .01). The other primary outcome, IENFD in the distal leg, remained stable, only improving by 0.1 (4.1) fibers/mm (P = .92).

Meanwhile, the primary outcomes for CAN remained stable with a mean E/I ratio of −0.01 (0.1; P = .89). Retinopathy, measured by mean deviation using frequency doubling technology (FDT) also remained stable with a deviation of −0.2 (3.0; P = .52).

Multiple secondary CAN outcomes showed improvement, and linear regression revealed that a greater reduction in fasting glucose was associated with improvements in retinopathy.

“Our findings probably indicate an improvement compared with the natural history of worsening PN, CAN, and retinopathy over time,” the authors said, citing previous studies.

A total of 163 individuals participated in the study, of which 127 (77.9%) successfully completed all baseline visits and underwent bariatric surgery. Of these 127 participants, 79 (62.2%) completed 2-year follow-up visits in person, while an additional 22 participants completed partial virtual measures due to COVID-19, resulting in a follow-up completion rate of 79.5%.

After undergoing bariatric surgery, several participants experienced difficulties in tolerating glucose tolerance testing due to anatomical changes resulting from the surgery. As a result, data collection for these tests was discontinued after June 2018. Of the 79 participants who successfully completed in-person follow-up visits, 71 (89.9%) had undergone sleeve gastrectomy, and 8 (10.1%) had undergone gastric bypass surgery.

Among the 79 participants who completed in-person follow-up, the mean (SD) age was 46.0 (11.3) years. Most of these participants were female (73.4%), White (79.7%), and non-Hispanic (98.7%). The authors observed no significant demographic differences among participants who completed in-person follow-up, virtual follow-up, or were lost to follow-up.

The authors also observed that changes in fasting glucose levels were associated with improvements in retinopathy, but that no other metabolic changes were correlated with measures of diabetes complications. Additionally, bariatric surgery was shown to have positive effects on several patient-oriented outcomes, including patient-reported quality of life, pain, and depression.

“Our study demonstrates that bariatric surgery may be an effective approach to reverse PN in individuals with obesity, either through the direct impact of metabolic improvement or other beneficial effects of bariatric surgery,” the authors concluded. “Given the natural history of worsening CAN and retinopathy, stability in these complications probably indicates a successful result; however, randomised controlled trials are needed to confirm these findings. For retinopathy, a specific reduction in hyperglycaemia following bariatric surgery is probably required to reverse this complication.”

Reference

Reynolds EL, Watanabe M, Banerjee M, et al. The effect of surgical weight loss on diabetes complications in individuals with class II/III obesity. Diabetologia. 2023;1-16. doi:10.1007/s00125-023-05899-3