Bariatric surgery and prevention of type 2 diabetes in Swedish obese subjects.
BACKGROUND
Weight loss protects against type 2 diabetes but is hard to maintain with behavioral modification alone. In an analysis of data from a nonrandomized, prospective, controlled study, we examined the effects of bariatric surgery on the prevention of type 2 diabetes.


METHODS
In this analysis, we included 1658 patients who underwent bariatric surgery and 1771 obese matched controls (with matching performed on a group, rather than individual, level). None of the participants had diabetes at baseline. Patients in the bariatric-surgery cohort underwent banding (19%), vertical banded gastroplasty (69%), or gastric bypass (12%); nonrandomized, matched, prospective controls received usual care. Participants were 37 to 60 years of age, and the body-mass index (BMI; the weight in kilograms divided by the square of the height in meters) was 34 or more in men and 38 or more in women. This analysis focused on the rate of incident type 2 diabetes, which was a prespecified secondary end point in the main study. At the time of this analysis (January 1, 2012), participants had been followed for up to 15 years. Despite matching, some baseline characteristics differed significantly between the groups; the baseline body weight was higher and risk factors were more pronounced in the bariatric-surgery group than in the control group. At 15 years, 36.2% of the original participants had dropped out of the study, and 30.9% had not yet reached the time for their 15-year follow-up examination.


RESULTS
During the follow-up period, type 2 diabetes developed in 392 participants in the control group and in 110 in the bariatric-surgery group, corresponding to incidence rates of 28.4 cases per 1000 person-years and 6.8 cases per 1000 person-years, respectively (adjusted hazard ratio with bariatric surgery, 0.17; 95% confidence interval, 0.13 to 0.21; P<0.001). The effect of bariatric surgery was influenced by the presence or absence of impaired fasting glucose (P=0.002 for the interaction) but not by BMI (P=0.54). Sensitivity analyses, including end-point imputations, did not change the overall conclusions. The postoperative mortality was 0.2%, and 2.8% of patients who underwent bariatric surgery required reoperation within 90 days owing to complications.


CONCLUSIONS
Bariatric surgery appears to be markedly more efficient than usual care in the prevention of type 2 diabetes in obese persons. (Funded by the Swedish Research Council and others; ClinicalTrials.gov number, NCT01479452.).
Institute of Medicine, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
Lena M S
LM
Carlsson
Markku
M
Peltonen
Sofie
S
Ahlin
Åsa
Å
Anveden
Claude
C
Bouchard
Björn
B
Carlsson
Peter
P
Jacobson
Hans
H
Lönroth
Cristina
C
Maglio
Ingmar
I
Näslund
Carlo
C
Pirazzi
Stefano
S
Romeo
Kajsa
K
Sjöholm
Elisabeth
E
Sjöström
Hans
H
Wedel
Per-Arne
PA
Svensson
Lars
L
Sjöström
D000328:Adult; D050110:Bariatric Surgery; D015992:Body Mass Index; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology / Q000517:prevention & control*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications / Q000601:surgery* / Q000628:therapy; D011183:Postoperative Complications / Q000401:mortality / Q000601:surgery; D011446:Prospective Studies; D012086:Reoperation / Q000706:statistics & numerical data; D012307:Risk Factors; D015431:Weight Loss