What is reactive hypoglycemia?

Dumping syndrome can be a side effect of a Roux-en-Y gastric bypass (RYGB).  It occurs due to the new, altered anatomy in which a small gastric pouch is created and is then connected to a limb of the small intestine (the Roux limb).  As a result of this new connection, there can be rapid gastric emptying, with the delivery of food particles rapidly into the small intestine.  Dumping syndrome does NOT typically occur with a sleeve gastrectomy, a SADI-S, or a duodenal switch (BPD/DS). In these surgeries, the pylorus, the natural valve of the stomach, is preserved.  The pylorus regulates the flow of food into the small intestines and therefore the pylorus prevents the rush of food into the small intestines that causes dumping syndrome. 

Dumping syndrome is divided into two stages, early and late symptoms.  In the early stage, the rapid transit of food particles into the small intestine causes fluid to shift into the small intestine.  More fluid within the intestine causes diarrhea.  The increased loss of fluid can also lead to lower blood pressure and feeling faint. This is called early dumping syndrome because the side effects are felt very soon after eating.

Late dumping syndrome is more hormonal mediated.  Reactive hypoglycemia is a hallmark of late dumping syndrome.  It is termed “late” because the symptoms are more delayed after eating.  Due to the rapid influx of food into the small intestines, the blood sugar levels quickly spike upwards.  The body senses this drastic upward spike in blood sugar and releases a flood of insulin in its attempt to bring down the blood sugar levels.  However, the body essentially releases too much insulin and as a result, the blood sugars crash hard.  This is called reactive hypoglycemia because the body is reacting to the rapid food influx.  In addition, with weight loss, patients also have decreased glycogen stores, which are the body’s natural storage form of glucose.  Without glycogen stores, the body cannot break down glycogen to quickly release glucose back into the body to help with the low glucose levels. Patients with reactive hypoglycemia can have blood sugars in their 30s or 40s.  Hypoglycemia symptoms include feeling faint or lightheaded, low blood pressure, and feeling sweaty or clammy.  Patients with hypoglycemia can also be more irritable or have other mood changes. 

The treatment for dumping syndrome and reactive hypoglycemia heavily focuses first on dietary and lifestyle changes.  Patients are advised to eat multiple small meals throughout the day and focus on low glycemic index foods.  This means a high protein and high fiber diet while avoiding simple carbohydrates and sugars.  Eating slowly helps prevent the rapid transit of food into the small intestine. Dietitians can be especially helpful in creating diets that can help prevent reactive hypoglycemia.  

Oftentimes, dietary changes alone can prevent further episodes of reactive hypoglycemia. However, if dietary changes are not enough, we can add medications. Classically, the medication used to treat reactive hypoglycemia was acarbose.  This medication works by preventing the breakdown of carbohydrates into sugars and can help prevent blood sugar spikes.  However, more recently, we have discovered that the GLP-1 receptor agonist (GLP-1 RA) medications are an excellent medical therapy for reactive hypoglycemia.  You probably know these medications better as Ozempic / Wegovy or Mounjaro / Zepbound.  By acting upon the GLP-1 receptors, these medications help prevent the spike in blood glucose.  By preventing the spike in blood glucose, the body does not release the flood of insulin and therefore, there is no bottoming out of the blood glucose values.  By keeping the blood sugars at a higher level, we can prevent hypoglycemia episodes.  GLP-1 RA medications are very effective in treating reactive hypoglycemia.  Talk to an endocrinologist about these medications for reactive hypoglycemia.

The final treatment option for reactive hypoglycemia or dumping syndrome is surgery.  Given how effective dietary changes, and now the GLP1 RA medications, are for dumping syndrome, only very rarely is surgery needed to treat reactive hypoglycemia.  Two surgical options include a Transoral Outlet Reduction (TORe) Procedure versus a reversal of the gastric bypass.  For anyone with refractory, difficult-to-control, reactive hypoglycemia, an endoscopy (EGD) is performed first to assess the RYGB anatomy.  If based on the endoscopy, the Gastro-jejunal anastomosis (the connection between the gastric pouch and the small intestine) is noted to be particularly wide, the patient may be a candidate for a TORe procedure.  In this endoscopic procedure, the anastomosis is made significantly smaller using suture and/or electrocautery. With a smaller opening, food is delivered into the small intestine much slower and this helps prevent dumping syndrome.  Interventional Gastroenterologists typically are the ones performing this procedure.

The final procedure to consider is a reversal of the RYGB.  I call this the option of last resort.  By reversing the gastric bypass, the gastric pouch is reconnected back to the bypassed stomach, restoring the normal transit of food into the small intestine through the pylorus.  In the majority of cases, this is very effective at preventing any further episodes of reactive hypoglycemia or dumping syndrome.  However, with the reversal of the RYGB, we also reverse all the other metabolic benefits of the RYGB. As a result, patients will often see a return of their disease of obesity and all related comorbidities, such as diabetes or high blood pressure.  Therefore, this is the option of very last resort.

Luckily, with the correct diet and sometimes the addition of the GLP1 RA medications, the vast majority of cases of dumping syndrome and reactive hypoglycemia can be managed.  Talk to your bariatric surgeon if you are having these symptoms and they can help guide you with the correct treatment!