Diabetes affects weight loss magnitude after bariatric surgery

The magnitude of weight loss following bariatric surgery for obesity may be reduced among individuals who have diabetes prior to surgery, according to a retrospective study presented at ENDO 2020.

Data on the study population was obtained from the Michigan Bariatric Surgery Cohort (MI-BASiC). The population comprised 714 adults with obesity (BMI >40 kg/m² or 35–39.9 kg/m² with comorbidities) who underwent bariatric surgery at the University of Michigan, Ann Arbor, Michigan, US, between January 2008 and November 2013.

Of these, 380 underwent gastric bypass (mean age 43.6 years, 80.3 percent female, mean BMI 47.3 kg/m²) and 334 sleeve gastrectomy (mean age 45.3 years, 77.5 percent female, mean BMI 49.9 kg/m²). Diabetes was present in 39.2 and 32.3 percent of patients who underwent gastric bypass and sleeve gastrectomy, respectively, with 11.8 and 8.7 percent, respectively, on insulin therapy.

Having diabetes pre-surgery did not affect the likelihood of achieving a BMI <30 kg/m² following bariatric surgery (p=0.0848). [ENDO 2020, abstract MON-590]

However, individuals without diabetes at baseline were significantly more likely to achieve an excess body weight loss (EBWL) of ≥50 percent compared with those with diabetes (odds ratio, 1.56, 95 percent confidence interval [CI], 1.18–2.08; p=0.0021).

Regardless of type of surgery, patients with diabetes at baseline had their BMI loss diminished by 1.2 points (95 percent CI, 0.21–2.20) compared with non-diabetics, which translated to 10–15 percent total loss of BMI points.

After adjusting for age, time, type of surgery, gender, and baseline weight, absolute weight loss (p=0.0110), percentage of total weight loss (p=0.0089), and percentage of excess weight loss (p=0.0365) were significantly lower among individuals with diabetes compared with non-diabetics over a 5-year follow-up period.

“Among patients who present with both obesity and diabetes, bariatric surgery can lead to remission of both these diseases,” said the researchers.

“However, which population could have the most benefit from the surgery, and the possible impact of diabetes on the success of their weight loss surgery is still unknown,” said study lead researcher Professor Elif Oral from the University of Michigan.

“Our study suggests that having bariatric surgery before developing diabetes may result in greater weight loss from the surgery, and together with data that is available from other studies, bariatric surgery may potentially prevent or delay diabetes from developing,” she added, calling for further research into identifying the reasons for the reduction in bariatric surgery-induced weight loss magnitude with diabetes. [Singapore Med J 2018;59:472‐475; Curr Obes Rep 2015;4:287-302; N Engl J Med 2012;367:695-704]