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Bariatric Surgery and Diabetes

By Dana Babeu, R.D. | September 8, 2015

New Jersey Bariatric Center® patient Deborah is a weight loss surgery success story. She speaks regularly at our bariatric surgery seminars, telling people about her weight loss journey. One recent morning, I sat in on one of these seminars in our office and listened as she asked attendees to raise their hands if they or someone in their family had been diagnosed with type 2 diabetes. Almost every hand in the room was raised. Deborah went on to tell the story about how she had battled with her weight and rising blood sugars for years before finally being told that she, too, was a diabetic. She tried to manage her sugars through lifestyle changes, but only stuck to diets for a short time before giving up. The excess weight made exercise difficult and soon Deborah found herself on multiple medications to help manage her disease. Depressed and fed up, she attended our information session on bariatric surgery.  When the doctor spoke about the surgery’s potential for improving blood sugar control and eliminating the need for multiple blood pressure, cholesterol and diabetes medications, Deborah felt hopeful for the first time in years.

Deborah’s story is not an unusual one. Diabetes now affects nearly 1 in 3 adult Americans and an estimated 1 billion people worldwide.  Obesity, the primary trigger for developing type 2 diabetes, also affects about a third of the population in this country. So closely linked are the two diseases that the term “diabesity” was coined to refer to the growing epidemic. While various medications, along with diet and exercise, can result in somewhat improved control, they often cause unpleasant side effects.  Some also require consistent monitoring of blood sugar levels, carbohydrate counting and precise meal timing. I have worked with many patients over the years who attempted to change their diet and lifestyle in order to reduce or eliminate the need for diabetes medications.  And while not impossible to do, the majority of patients find the necessary changes are difficult to maintain over time.  For many, this means a future of finger sticks, medication, medical visits, and blood sugar highs and lows.

That could have been the end of the story for many diabetics. But about 10 years ago, doctors began to notice some remarkable trends in patients who’d had bariatric surgery. Within days of having gastric bypass surgery for weight loss, many diabetic patients saw their blood sugar and insulin levels return to normal.  Many no longer required any diabetes medicine, and in some cases reduced or eliminated the need for blood pressure and cholesterol medications, as well.  It’s something the team at New Jersey Bariatric Center® sees weekly, but don’t just take my word for it. Let’s explore what we know about diabetes and gastric bypass, gastric sleeve and gastric band.

What causes type 2 diabetes?

Diabetes is a malfunction of the endocrine system, specifically the body’s ability to properly break down or metabolize carbohydrates and sugars.  When we eat carb-containing foods such as bread, potatoes, cake and fruit, they are digested into molecules of simple sugar called glucose. As a result, blood sugar rises. This signals the pancreas to release insulin, which acts like a key to “unlock the doors” of our cells so the circulating molecules of glucose can enter and be processed. Once all the incoming glucose has been taken up by cells, blood sugar returns to normal and the pancreas no longer pushes out insulin. Now imagine this same scenario, but the keys get all mixed up and there’s no way to unlock the cell doors.  Molecules of sugar keep circulating in the bloodstream, which causes the pancreas to surge out even more insulin.  But the insulin isn’t able to do its job and blood sugar levels remain chronically high.  Over time, these episodes of high blood sugar lead to increased fat storage and diabetes, as well as stress on the kidneys, nervous and circulatory systems.

Study Finds Gastric Sleeve and Gastric Bypass Improve Diabetes

Several first-of-their-kind studies recently have compared weight loss surgery to traditional medical therapies for diabetes to determine whether bariatric surgery can in fact reverse type 2 diabetes. While it cannot be guaranteed in any case, the results are promising.

The Stampede study, conducted by researchers at the Cleveland Clinic in 2011, enrolled 150 obese patients with poorly controlled type 2 diabetes. Patients underwent either gastric bypass surgery or sleeve gastrectomy. The results were compared to traditional medical therapies aimed at achieving weight loss and blood sugar control through exercise, nutrition counseling and the addition of diabetes medicine when necessary. Following surgery, close to 40% of bypass patients and a quarter of the sleeve gastrectomy group had achieved desirable blood sugar levels below the target set by the American Diabetes Association. Most no longer needed diabetes medications either. Compared with only about a 5% success rate in the traditional treatment group, these results are significant.  Add to that the results of a three-year follow-up that found 55 percent of the medical therapy group required insulin at that time, compared to less than 10 percent of surgery patients.  And in many cases among the surgery group, there was evidence of improved pancreatic function and increased natural insulin production.  Protein levels in the urine, an indicator of kidney function, were also significantly lower among bypass patients.  Researchers consider this evidence remarkable in that it represents a reversal of some patients’ diabetes, as opposed to just treating or managing symptoms.  But understanding exactly why and how it works is still something of a mystery.

Fat loss, particularly in the abdominal area, may be partly responsible for the anti-diabetic effect.  As abdominal fat decreases, insulin sensitivity tends to improve, as well as post-meal insulin production by the pancreas.  It is likely, however, there are other factors at work as well since in many cases blood sugar levels normalize within days of surgery, long before any significant weight loss has occurred.  This has led doctors and researchers to theorize that surgical changes to the anatomy of the GI tract and resulting alterations in food delivery may hold the key to explaining why bariatric surgery works where so many other interventions fall short.  We already know that rearranging digestive organs results in changes to an individual’s populations of gut bacteria, production of proteins and hormone levels.  These, in turn, affect the way food smells, tastes and is tolerated by many post-operative patients.  Because diabetes is a disease of the endocrine system, it makes sense that hormone fluctuations in the GI tract could influence insulin and blood sugar levels, too.

Another area of intense research is the role gut bacteria, or the microbiome as it’s known, play in obesity, inflammation and disease.  Microbial DNA outnumber our human DNA by an incredible 100 to 1.  And you thought your genes were running the show?  Think again.  So when we talk about factors such as metabolism, weight status, immune function, disease risk, appetite and inflammation, we are actually referring to the influence of our resident bacteria.  It is quite possible that surgical alterations to the GI tract may cause a favorable shift in the populations of microbes residing in the gut.  This, in turn, could influence the way the body breaks down and utilizes nutrients from food following surgery.

If current trends continue, one third of all Americans could have type 2 diabetes by the year 2050.  But for the many patients and families affected by the disease, this new way of thinking about diabetes treatment offers a lot of potential hope.  Just ask Deborah.  Almost two years after having a sleeve gastrectomy, she maintains an 85-pound weight loss, walks for several hours per week without pain and no longer requires diabetes or cholesterol medications.  She says the best part of the new and improved Deborah is being able to keep up with her grandchildren and not spending her days going from one doctor’s appointment to another.   When she overindulges on occasion, she now knows how to get back on track before things get out of hand.  Regularly attending support groups and keeping follow-up visits with her nutritionist and surgeon help her stay committed to her healthy lifestyle.  And Deborah shares her story whenever she can, hoping to inspire others who feel they have no choice but to live with diabetes.


  1. First accessed 5/28/2015 - Medical News Today.  Weight loss surgery treats type 2 diabetes in obese patients. Published 4/1/2015.
  2. Bariatric Surgery versus Intensive Medical Therapy for Diabetes - 3-Year Outcomes, Philip R. Schauer, et al., for the STAMPEDE Investigators, NEJM online 31 March 2014, DOI: 10.1056/NEJMoa1401329, Abstract. Accessed 5/30/15.
  3. Bariatric Surgery for Type 2 Diabetes Reversal: The Risks, Andrei Keidar, Diabetes Care May 2011 vol. 34 no. Supplement 2 S361-S266.
Dana Babeu, RD, is a registered dietitian at New Jersey Bariatric Center, a medical & surgical weight loss center with offices in Springfield, Somerville, Hoboken, East Brunswick, Hackettstown and Sparta, New Jersey. She provides pre-operative and post-operative nutritional counseling to New Jersey Bariatric Center’s Gastric Bypass, Gastric Sleeve, LAP-BAND (gastric band) and revision patients, in addition to dietary counseling for patients in our Medical Weight Loss program.
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