Diabetes & Weight Loss Surgery

How Does Weight Loss Surgery Affect Diabetes

More than 90% of diabetics in the United States are type 2. With this type of diabetes, your body produces more insulin than typical but can't use it as well as it should, resulting in sugar build-up in the blood and tissues. Diabetes can cause serious health complications including heart disease, blindness, kidney failure, neuropathy and lower-extremity amputations. It is the sixth leading cause of death in the United States. Type 2 diabetes is linked to obesity and is largely preventable.

Diabetes & Conservative Therapy

Weight loss should be the primary objective of the treatment of type 2 diabetes, but it is rarely achieved. In fact, weight gain is a major complication of current medical treatment of diabetes (Metformin, etc.). Unfortunately, it appears that weight gain is the price paid for short term improvement in glucose control. For some patients, this creates a downward spiral in diabetes management.>

In a study published in the Journal of the American Medical Association (JAMA), a group of 4,075 diabetics followed for nine years demonstrated a deterioration of diabetes control with medical treatment such as diet, metformin or insulin (1). Despite adherence to this regimen, the disease continued to progress, specifically with the treatment goals of maintaining a fasting blood sugar (FBG) below 140 and HbA1C less than 7:>

9 Year Follow-Up (4,075 Patients) FBG < 140 >HbA1C < 7>
Diet> 8% 9%
Insulin 42% 28%
Metformin 24% 24%

Only 50% of patients met this goal at three years and this decreased to 25% after 9 years.

How Does Weight Loss Surgery Affect Diabetes?

Weight loss as a result of bariatric surgery has a documented, positive effect on the management of type 2 diabetes. In fact, studies have shown that weight loss surgery achieves better blood glucose control than standard medical care alone.

A meta-analysis of studies done between 2003 and 2012 showed that diabetes remission rates after weight loss surgery were even higher than previously reported (2). A total of 164 studies were included (37 randomized clinical trials and 127 observational studies). Analyses included 161,756 patients with a mean age of 44.56 years and body mass index (BMI) of 45.62. Data from gastric bypass, adjustable gastric band and sleeve gastrectomy surgeries was analyzed. The study reported a 92% diabetes remission rate for randomized clinical trials (86% with observational studies).   

In another study, patients who had the sleeve gastrectomy achieved better blood glucose control than with standard medical care alone (3). Those who had surgery saw significant improvements in BMI (decreasing from 46 to 34 over two years) and HbA1c (decreasing from 7.25% to 5.98% over two years). A significant increase in HDL ("good") cholesterol was also seen in patients who had surgery.
In addition, after two years, 76% of patients who had the sleeve gastrectomy discontinued or reduced their diabetes medications, compared with 26% of patients who received medical treatment only. In fact, 52% of patients who didn't have surgery actually increased their medication over the 2-year study.
Type 2 Diabetes Remission Rates by Surgery
Surgery Type
Remission Rate
Remission Mechanism
Duodenal switch
  • Duodenal exclusion
  • Removal of 80% of stomach reduces ghrelin-producing cells (hunger hormone)
  • Faster delivery of nutrients to the distal small intestine may release hormonal factors (GLP-1, PYY) that improve glycemic control
  • Weight loss
Single-anastomosis duodenal switch
  • Similar results as the standard duodenal switch on preliminary studies. Long-term results are awaited.
  • Duodenal exclusion
  • Removal of 85% of stomach reduces ghrelin-producing cells (hunger hormone)
  • Faster delivery of nutrients to the small intestine may release hormonal factors (GLP-1, PYY) that improve glycemic control
  • Weight loss
Sleeve gastrectomy
  • Primarily by weight loss
  • Removal of 85% of stomach reduces ghrelin-producing cells
  • Faster transit time with the Sleeve helps deliver nutrients to the distal small intestine may help release hormonal factors (GLP-1, PYY) that improve sugar control 
Gastric bypass
  • Bypasses duodenum and proximal jejunum (areas that are efficient in the absorption of carbohydrates)
  • Bypassing duodenum may release hormonal factors that improve diabetes control
  • Abolition of ghrelin level fluctuation
  • Weight loss
Early surgical intervention is the key to improving diabetes remission. In a study from the Annals of Surgery (2003) patients who had their surgery within 5 years of the onset of diabetes, especially if they were diet controlled or on medications other than insulin achieved greater than 95% remission rates (4).
Improved (%)
Resolved (%)
Severity of Diabetes
Borderline Diabetics (n=14)
Diet Controlled (n=32)
Oral Drug Controlled (n=93)
On Insulin (n=52)
Duration as Diabetic
< 5 years (n=119)
     6 - 10 years (n=44)
> 10 years (n=28)
  1. Turner R. C.; Cull C. A., Frighi V., Holman R. R. Glycemic control with diet, sulfonylurea, metformin, or insulin in patients with type 2 diabetes mellitus : progressive requirement for multiple therapies (UKPDS 49). UK Prospective Diabetes Study (UKPDS) Group. JAMA, 1999 Jun 2, 281 (21): 2005-12.
  2. Chang S, Stoll CT, Song J, Varela J, Eagon CJ, Colditz GA. The Effectiveness and Risks of Bariatric Surgery: An Updated Systematic Review and Meta-analysis, 2003-2012. JAMA Surg. 2014;149(3):275-287. doi:10.1001/jamasurg.2013.3654.
  3. "Better Long-term Diabetes Outcomes with Sleeve Gastrectomy vs. Medical Management." Healio Endocrinology, 7 July 2014. Web. 30 July 2014.
  4. Schauer PR, Burguera B, Ikramuddin S, et al. Effect of Laparoscopic Roux-En Y Gastric Bypass on Type 2 Diabetes Mellitus. Annals of Surgery 2003;238(4):467-485. doi:10.1097/01.sla.0000089851.41115.1b.

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