Bariatric Surgery Significantly Reduces Risk of Developing Major Obesity-Related Comorbidities: Insights from a Large Veterans Cohort

Highlight

• Bariatric surgery in obese veterans reduces the incidence of type 2 diabetes (T2D), hypertension, hyperlipidemia, obstructive sleep apnea (OSA), and metabolic dysfunction-associated steatotic liver disease (MASLD) compared to a weight management program (WMP).
• At 5 years, surgery patients exhibited approximately 40% to 79% lower risk for developing these metabolic comorbidities.
• The study analyzed over 269,000 veterans across 128 centers, providing robust real-world evidence supporting bariatric surgery for obesity-related risk mitigation.

Study Background and Disease Burden

Obesity remains a major public health crisis in the United States, disproportionately affecting metabolic health and predisposing individuals to a cluster of comorbidities including type 2 diabetes (T2D), hypertension, dyslipidemia, obstructive sleep apnea (OSA), and metabolic dysfunction-associated steatotic liver disease (MASLD). These obesity-related conditions significantly increase morbidity, mortality, and healthcare costs. While bariatric surgery has been established as an effective treatment for weight loss and reversing existing metabolic diseases, there has been limited large-scale data quantifying its preventive effect on the incident development of these major comorbidities among eligible patients. Understanding how bariatric surgery compares to non-surgical weight management is critical for guiding treatment selection and healthcare policy.

Study Design

This retrospective, multicenter cohort study analyzed electronic health record data from the Veterans Health Administration’s Corporate Data Warehouse, encompassing 128 centers across the United States. Adult veterans aged 18 years or older with a body mass index (BMI) of 30 or higher plus at least one existing metabolic comorbidity, or BMI ≥35 regardless of comorbidities, were included if they underwent bariatric surgery (Roux-en-Y gastric bypass or sleeve gastrectomy) or enrolled in the Veterans MOVE! weight management program (WMP) between January 1, 2008, and December 31, 2023. Patients with all five metabolic comorbidities at baseline or missing critical data were excluded to focus on incident outcomes.

The primary exposure compared was bariatric surgery versus non-surgical WMP. The main outcome measures were incident diagnoses of five metabolic comorbidities: T2D, hypertension, hyperlipidemia, OSA, and MASLD, assessed longitudinally with a median follow-up exceeding 9 years.

Key Findings

The study cohort included 269,470 veterans: 5,813 underwent bariatric surgery and 263,657 were enrolled in the WMP. The majority were male (87.1%) with a median age of 57 years. Median follow-up duration was approximately 113 months.

At 5 years, incidence rates of new metabolic diagnoses per 1000 person-years were substantially lower in the bariatric surgery group compared to the WMP group:

Comorbidity	WMP Incidence Rate	Bariatric Surgery Incidence Rate	Hazard Ratio (HR) with Surgery	Risk Reduction (%)
Hypertension	8.89	3.35	0.41 (95% CI, 0.33-0.51)	58.8%
Hyperlipidemia	9.67	4.85	0.49 (95% CI, 0.42-0.58)	50.5%
Type 2 Diabetes (T2D)	4.29	1.06	0.21 (95% CI, 0.18-0.26)	79.2%
Obstructive Sleep Apnea (OSA)	3.99	3.43	0.43 (95% CI, 0.35-0.52)	56.9%
MASLD	2.44	2.01	0.60 (95% CI, 0.49-0.73)	40.4%

All hazard ratios were statistically significant, indicating a robust association between bariatric surgery and reduction in incident metabolic comorbidities. A subgroup analysis focusing on female veterans showed consistent results, underscoring the generalizability across sexes.

This study is notable for its large sample size, extended follow-up, real-world VHA population, and comprehensive capture of key metabolic outcomes. The comparison group of WMP participants also provides practical insight into how surgical and non-surgical approaches differ in preventing new-onset metabolic disease rather than just treating existing conditions.

Expert Commentary

The findings from this study align with current clinical understanding that bariatric surgery induces profound metabolic effects beyond caloric restriction, including hormonal changes that improve insulin sensitivity and lipid metabolism. The marked reduction in T2D incidence (over 79%) particularly reaffirms surgery’s role as a pivotal intervention for diabetes prevention in obese populations.

However, some limitations include retrospective design and potential selection bias; patients electing surgery may have differing health behaviors or access. Additionally, as the cohort primarily comprises male veterans, findings may be less generalizable to broader populations, although the consistency in females mitigates this concern.

This research complements guideline recommendations advocating bariatric surgery for individuals with BMI ≥40 or BMI ≥35 with comorbidities. It also underscores the importance of addressing obesity early to prevent progression to multiple metabolic diseases that have long-term cardiovascular and hepatic consequences.

Conclusion

This extensive Veterans Health Administration cohort study demonstrates that bariatric surgery is associated with a significantly reduced risk of developing major obesity-related metabolic comorbidities compared with an intensive medical weight management program. These data highlight bariatric surgery’s effectiveness not only in treating but also in preventing the onset of T2D, hypertension, hyperlipidemia, OSA, and MASLD in high-risk patients. As obesity prevalence continues to grow, integrating bariatric surgery into comprehensive obesity management could substantially alleviate long-term healthcare burdens by mitigating incident metabolic diseases.

Funding and Trial Registration

The study was supported by institutional and Veterans Health Administration resources. Further information regarding funding and trial registration is available in the original publication.

References

Bader AL, Hsu JY, Altieri MS, Vollmer CM, Lewis JD, Kaplan DE, Mahmud N. Bariatric Surgery and Incident Development of Obesity-Related Comorbidities. JAMA Netw Open. 2025 Sep 2;8(9):e2530787. doi: 10.1001/jamanetworkopen.2025.30787. PMID: 40924423; PMCID: PMC12421336.