Gastric Sleeve and Type 2 Diabetes: What the Trials Show

In randomized trials, a gastric sleeve lowered blood sugar more than medication and lifestyle treatment alone, and patients used fewer diabetes medicines for years afterwards. In the STAMPEDE trial, 23% of sleeve patients had a hemoglobin A1c of 6.0% or less at five years, against 5% of those on intensive medical therapy. Results were broadly similar to gastric bypass, and remission does not last for everyone.

Sleeve compared with medication alone

Hemoglobin A1c (HbA1c) is a blood test that reflects average blood sugar over about three months. It is the main yardstick in these trials.

STAMPEDE

This trial (Schauer and colleagues, New England Journal of Medicine, 2017) randomized 150 people with type 2 diabetes and a body mass index (BMI) of 27 to 43 to intensive medical therapy alone, or medical therapy plus a gastric bypass or a sleeve. Their diabetes was not well controlled at the start: average HbA1c was 9.2%, and 44% were using insulin. Five-year results for the 134 people who completed follow-up:

At 5 years	Medical therapy	Sleeve	Gastric bypass
HbA1c 6.0% or less, with or without medicines	5.3%	23.4%	28.6%
HbA1c 6.0% or less with no diabetes medicines	0%	14.9%	22.4%
Average change in HbA1c (percentage points)	-0.3	-2.1	-2.1
Change in body weight	-5%	-19%	-23%

The 6.0% target is strict, which is partly why the percentages reaching it look modest. After the trial's adjustment for multiple comparisons, the gap between sleeve and medical therapy on that target was no longer statistically significant (P = 0.07). The average fall in HbA1c of about two points in both surgical groups, compared with 0.3 on medical therapy, was significant.

ARMMS-T2D

This study (Courcoulas and colleagues, JAMA, 2024) pooled four U.S. randomized trials and followed 262 people for up to 12 years. The surgery group included bypass, sleeve and adjustable band patients. At seven years, HbA1c had fallen by 1.6 points in the surgery group and 0.2 in the medical and lifestyle group. Diabetes remission was recorded in 18.2% of the surgery group and 6.2% of the medical group at seven years, and in 12.7% and 0.0% at twelve years. A quarter of the people assigned to medical treatment went on to have surgery during follow-up.

Sleeve compared with gastric bypass

Three randomized trials compared the two operations directly, and none found a statistically significant difference in diabetes remission or the main blood sugar target:

• STAMPEDE, 5 years. The gap between sleeve and bypass on the main HbA1c target was not significant. Bypass patients lost more weight.
• SM-BOSS, 5 years. In this Swiss trial (Peterli and colleagues, JAMA, 2018), diabetes was in complete remission in 16 of 26 sleeve patients (61.5%) and 19 of 28 bypass patients (67.9%).
• SLEEVEPASS, 10 years. In this Finnish trial (Salminen and colleagues, JAMA Surgery, 2022), remission was recorded in 11 of 42 sleeve patients (26%) and 13 of 39 bypass patients (33%).

The remission percentages differ widely between trials, which had different patients and lengths of follow-up, so they should not be compared with one another. The numbers of people with diabetes in SM-BOSS and SLEEVEPASS were small, and a real difference between the operations could have been missed. In ARMMS-T2D, the seven-year fall in HbA1c was 2.0 points after a sleeve and 1.7 after a bypass, which was not a significant difference. The other trade-offs between the two procedures, including reflux, are covered on our gastric bypass versus gastric sleeve page.

Who tends to do better, and what can go wrong

In STAMPEDE, having diabetes for less than eight years was a significant predictor of reaching the HbA1c target. Greater weight loss in the first year was also linked to success. In SLEEVEPASS, remission was more common the shorter the time someone had had diabetes before surgery.

Remission is not the same as cure. The ten-year and twelve-year figures above show that many people are not in remission years later, so keep up regular HbA1c checks even when you take no diabetes medicine.

Surgery has its own costs. In STAMPEDE, anemia, described as mild, was recorded in 49% of the sleeve group over five years, against 16% of the medical group. ARMMS-T2D found anemia, fractures and gastrointestinal problems more often after surgery. Supplements and blood tests help prevent and catch deficiencies; see vitamins and lab tests after a sleeve. Surgical complications are described on our gastric sleeve risks page. A sleeve cannot be reversed.

Where newer diabetes medicines fit

The trials above enrolled patients between 2007 and 2013, so they do not tell us how a sleeve compares with the GLP-1 medicines widely used today. Ozempic and Mounjaro are FDA approved for type 2 diabetes; Wegovy and Zepbound are approved for chronic weight management. See gastric sleeve surgery versus Ozempic and GLP-1 medications after bariatric surgery.

Who qualifies, and getting ready

The 2022 ASMBS/IFSO guidelines recommend metabolic and bariatric surgery for people with type 2 diabetes and a BMI above 30. Insurers may still apply criteria that begin at a BMI of 35; see gastric sleeve with a BMI of 30 to 35.

The 2019 clinical practice guideline from ASMBS and four other societies gives a reasonable pre-surgery target of an HbA1c of 6.5% to 7.0% or less. It allows 7% to 8% for people with advanced complications, extensive other conditions or long-standing diabetes that has been hard to control, and leaves the need and timing of surgery to clinical judgment when HbA1c is above 8%. Ask the office whether Dr. Davtyan sets an HbA1c level you must reach before surgery.

Diabetes medicines change right after a sleeve because you eat so little. The 2019 guideline says that immediately after surgery sulfonylureas such as glipizide or glimepiride should be stopped and insulin doses adjusted to lower the risk of low blood sugar. Before surgery, ask who will adjust your medicines afterwards: your surgeon, your endocrinologist or your primary care doctor. Have a written plan before you leave the hospital.

Shakiness, sweating, confusion or a meter reading below 70 mg/dL can mean low blood sugar: treat it as you have been taught and call the doctor who manages your diabetes the same day. If someone with low blood sugar cannot swallow, is unconscious or stays confused, call 911.

Frequently asked questions

Can a gastric sleeve put type 2 diabetes into remission?

For some people, yes. In the trials above, remission after a sleeve ranged from about a quarter of patients at ten years in SLEEVEPASS to about six in ten at five years in SM-BOSS. Some others improved without reaching full remission. No one can tell you in advance which group you will be in.

Will I be able to stop insulin after a sleeve?

Some people do, and many reduce their dose. In STAMPEDE, 44% of participants used insulin at the start, and at five years the trial reports a change in insulin use of minus 34% in the sleeve group and minus 35% in the bypass group, against minus 13% with medical therapy. Never stop or cut insulin on your own; make changes with your doctor using your glucose readings.

Does a sleeve help type 1 diabetes?

The trials on this page studied type 2 diabetes only. Type 1 diabetes is caused by loss of insulin production, and weight loss does not restore it. Whether surgery is appropriate for someone with type 1 diabetes and obesity is an individual decision made for other health reasons. Insulin is still needed afterwards and requires close management around the operation.

How long does the improvement in blood sugar last?

It lasted for years on average in these trials, though not for everyone. In ARMMS-T2D, the surgery group still had an HbA1c 1.1 points lower than the medical group at twelve years, and remission was recorded in 12.7% at that point. Keeping up with follow-up visits and blood tests lets you and your doctors see any change early.

Talk with Dr. Davtyan in Rancho Cucamonga

Dr. David G. Davtyan, MD, FACS, FICS, FASMBS, is a bariatric surgeon with Davtyan Medical Weight Loss & Wellness at 8330 Red Oak Street, Suite 201, Rancho Cucamonga, CA 91730. Call 909-355-2525 or toll free 877-9-BE-SLIM (877-923-7546), or use our contact page. The first consultation is complimentary, and Hablamos Español. More topics are in our Rancho Cucamonga gastric sleeve guide.

Sources

• Schauer PR, et al. Bariatric Surgery versus Intensive Medical Therapy for Diabetes: 5-Year Outcomes (STAMPEDE). N Engl J Med. 2017
• Courcoulas AP, et al. Long-Term Outcomes of Medical Management vs Bariatric Surgery in Type 2 Diabetes (ARMMS-T2D). JAMA. 2024
• Salminen P, et al. Effect of Laparoscopic Sleeve Gastrectomy vs Roux-en-Y Gastric Bypass on Weight Loss, Comorbidities, and Reflux at 10 Years (SLEEVEPASS). JAMA Surg. 2022
• Peterli R, et al. Effect of Laparoscopic Sleeve Gastrectomy vs Laparoscopic Roux-en-Y Gastric Bypass on Weight Loss in Patients With Morbid Obesity (SM-BOSS). JAMA. 2018
• Eisenberg D, et al. 2022 ASMBS and IFSO: Indications for Metabolic and Bariatric Surgery. Obes Surg. 2023
• Mechanick JI, et al. Clinical practice guidelines for the perioperative nutrition, metabolic, and nonsurgical support of patients undergoing bariatric procedures, 2019 update. Endocr Pract. 2019 (full-text copy hosted by the Commission on Dietetic Registration)
• National Institute of Diabetes and Digestive and Kidney Diseases. Prescription Medications to Treat Overweight and Obesity

More in the Gastric Sleeve in Rancho Cucamonga guide

Start at the Gastric Sleeve in Rancho Cucamonga page, or go straight to a topic.

Understanding the sleeve

• Staple-Line Leak After Gastric Sleeve: Signs, Timing and Treatment
• Gastric Sleeve Stricture (Stenosis): Symptoms, Tests and Treatment
• Acid Reflux and GERD After Gastric Sleeve Surgery
• Hiatal Hernia and Gastric Sleeve Surgery
• Gallstones After Gastric Sleeve Surgery
• Hair Loss After Gastric Sleeve Surgery
• Nausea, Dehydration and Constipation After Gastric Sleeve Surgery
• Gastric Sleeve Emergency Warning Signs: When to Go to the ER
• Weight Regain After Gastric Sleeve: Why It Happens and What Can Be Done
• Vitamins and Lab Tests After a Gastric Sleeve
• Alcohol After a Gastric Sleeve: What Changes and What the Evidence Says
• Pregnancy After a Gastric Sleeve: Timing, Nutrition and Monitoring

Weighing your options

• Gastric Sleeve With a BMI of 30 to 34.9
• Gastric Sleeve With a BMI of 50 or More
• Gastric Sleeve Surgery After Age 60
• Gastric Sleeve and Type 2 Diabetes: What the Trials Show
• Tests Before Gastric Sleeve Surgery
• The pre-surgery liver diet before a gastric sleeve
• Insurance requirements for a gastric sleeve: how insurers decide
• What affects the cost of gastric sleeve surgery
• Converting a gastric sleeve to a gastric bypass
• Gastric sleeve in Mexico or near home: what to weigh
• Second opinions on gastric sleeve surgery: when and how
• Questions to ask a gastric sleeve surgeon

Getting care in Rancho Cucamonga

• Sleeve done elsewhere: how to move your follow-up care
• Gastric sleeve revision: reasons, tests and options
• Your first gastric sleeve consultation: what happens and what to bring
• From consultation to gastric sleeve surgery: the steps in order
• Gastric sleeve surgery day and the hospital stay
• Returning to work, driving, lifting and exercise after a gastric sleeve
• Gastric sleeve follow-up schedule: visits, labs and support
• Gastric sleeve care for Ontario, CA residents
• Gastric sleeve care for Fontana, CA residents
• Gastric sleeve care for Upland and Claremont residents
• Gastric sleeve care for Riverside and Corona residents
• Gastric sleeve care for San Bernardino and Redlands residents