Effect of Bariatric Surgery vs Medical Treatment on Type 2 Diabetes in Patients With Body Mass Index Lower Than 35: Five-Year Outcomes.
IMPORTANCE
It has been well recognized that metabolic surgery has short-term benefits for mildly obese patients with type 2 diabetes mellitus (T2DM), but how long these effects can be sustained is uncertain.


OBJECTIVE
To compare the 5-year efficacy between gastrointestinal metabolic surgery and medical treatment on glycemic control and diabetes remission in patients with T2DM and body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) lower than 35.


DESIGN, SETTING, AND PARTICIPANTS
This retrospective cohort study compares long-term outcomes for mildly obese patients with T2DM receiving metabolic surgery (n = 52) vs medical treatment (n = 299). The surgical group, enrolled from August 20, 2007, to June 25, 2008, and followed up through December 31, 2013, received standard sleeve gastrectomy (n = 19) or bypass (n = 33) procedures in a regional hospital. The medical group, selected from a nationwide community cohort that was recruited from August 27, 2003, to December 31, 2005, and followed up through December 31, 2012, was matched with the surgical group by age, BMI, and diabetes duration.


MAIN OUTCOMES AND MEASURES
Glycated hemoglobin (HbA1c) reduction and prolonged complete and partial diabetes remission (defined as HbA1c <6.0% and 6.0%-6.5% of total hemoglobin [Hb; to convert to proportion of total Hb, multiply by 0.01], respectively, for those who were exempted from any antidiabetic drugs for 5 years).


RESULTS
At the end of the fifth year, the surgical group had a mean weight loss of 21.0% (from a mean [SD] BMI of 31.0 [2.4] to 24.5 [2.7]), their mean (SD) HbA1c decreased from 9.1% (2.1%) to 6.3% (1.1%) of total Hb, 18 participants (36.0%) had complete remission, 14 (28.0%) had partial remission, 1 (1.9%) died, and 1 (1.9%) had end-stage renal disease. In the same follow-up period in the medical group, 3 (1.2%) had complete remission, 4 (1.6%) had partial remission, 9 (3.0%) died, and 2 (0.7%) had end-stage renal disease; their mean HbA1c remained around 8% of total Hb (mean [SD], 8.1% [1.8%] of total Hb at baseline and 8.0% [1.6%] of total Hb at 5 years), and BMI also stayed similar (mean [SD], 29.1 [2.4] at baseline and 28.8 [2.6] at 5 years). The HbA1c reduction and complete and partial remission rates were all significantly larger in the surgical group as compared with the medical group (all P < .001). However, the mortality rate and end-stage renal disease incidence were not significantly different in these 2 comparison groups (P = .66 and .37, respectively).


CONCLUSIONS AND RELEVANCE
For mildly obese patients with T2DM, the improvement in glycemic control from metabolic surgery lasts at least 5 years. However, the survival benefit and lifelong adverse outcomes require more than 5 years to be established.