Low Blood Sugar After WLS: Signs, Symptoms & Treatments

July 13, 2016

What is Low Blood Sugar?

Low blood sugar or hypoglycemia is defined as a blood sugar level less than 70mg/dL. Hypoglycemia commonly affects diabetics when exogenous insulin is taken without a meal containing a balance of carbohydrate, protein and fat.  Non-diabetic hypoglycemia includes both fasting hypoglycemia and reactive hypoglycemia.  Fasting hypoglycemia is related to certain disease states or the use of medications. Reactive hypoglycemia may occur in individuals who are pre-diabetic, have undergone certain gastrointestinal surgeries, such as bariatric surgery, or have rare enzyme deficiencies which inhibit the body’s ability to break down food.

Bariatric Surgery and Low Blood Sugar

Common bariatric procedures in the United States include the Lap-Band, Sleeve Gastrectomy, Roux-en-y Gastric Bypass and the Duodenal Switch. The Lap-Band and the Sleeve Gastrectomy aid in weight loss through restriction requiring minimal supplementation. However, due to consuming low amounts of calories, patients who undergo this restrictive procedure benefit from a daily multivitamin.

For Sleeve Gastrectomy patients, added calcium, in the form of calcium citrate, is recommended. This is due to low gastric acid in the stomach, which is required for optimal calcium absorption. Vitamin B12, also essential for absorption, is recommended due to the lack of intrinsic factor in the stomach.

Gastric Bypass and the Duodenal Switch provide a greater amount of weight loss due to their restrictive and malabsorptive nature.  In both procedures, a portion of the small intestine is bypassed leading to malabsorption of vitamins, minerals and, in the case for the Duodenal Switch, fat malabsorption.

For many years, the Roux-en-y Gastric Bypass has been a popular procedure used to treat morbid obesity. It was first developed in the 1960’s, and it continues to be performed, providing medical professionals the most research for clinical practice.  Common hypoglycemic events after consumption of a meal occur in Gastric Bypass patients in the context of dumping syndrome. However, recent studies have been published regarding hypoglycemic events several months to years following Gastric Bypass surgery known as hyperinsulinemic hypoglycemia.

Dumping syndrome occurs post-operatively in patients after ingesting a meal containing simple sugars. Simple sugars are rapidly digested and include foods such as jams, jellies, fruit drinks, table sugar, honey, and candies. Early dumping occurs as a result of rapid emptying of food into the jejunum, as the duodenum is bypassed as part of the surgical procedure. This rapid emptying response leads to symptoms such as abdominal pain, flushing, diarrhea and a rapid heart rate (tachycardia). Late dumping can occur 1-3 hours following a meal. This occurs due to a quick burst of insulin released from rapid absorption of simple sugars from the small intestine. Symptoms of late dumping include weakness, fatigue, and dizziness.

Hyperinsulinemic Hypoglycemia

Hyperinsulinemic hypoglycemia is diagnosed with continuous blood glucose monitoring through laboratory testing. A diagnosis of a true hypoglycemic disorder is a blood sugar level of less than 50-55mg/dl, with associated symptoms (fatigue, weakness, palpitations and sweating). Once laboratory tests are confirmed, imaging studies, such as a transabdominal sonogram and computed tomography scans are taken. These tests are used to rule out the presence of insulinoma (a tumor in the pancreas that produces excessive amounts of insulin). Hyperinsulinemic hypoglycemia can occur months to years following the Gastric Bypass surgery.

A research study by Abrahamsson, Engstrom, Sundbom and Karlsson (2015) was conducted to investigate the daily blood sugar variation and frequency of hypoglycemic symptoms after a meal in Gastric Bypass and Duodenal Switch patients.  The study involved three groups. 15 post-Gastric Bypass patients with a median 1.5 years post-surgery, 15 post-Duodenal Switch patients with a median of 2.0 years post-surgery and 15 control patients who were matched for a similar body mass index (BMI). For this study, a hypoglycemic episode was defined as occurring 4 hours after a meal. Hypoglycemic symptoms were characterized as experiencing the following: hunger, sweating, palpitations, weakness, tremors, anxiety, irritability, personality change, confusion, seizures and loss of consciousness.

Participants were required to continue their normal diet while keeping a food diary. They recorded the types of meals consumed, times when they were consumed, portion sizes and any experiences in a hypoglycemic state. Blood sugar was measured through continuous glucose monitoring during a three-day intervention period.

The researchers found that the Gastric Bypass group and the Duodenal Switch group had higher numbers of blood sugar less than 60mg/dl and longer times in a hypoglycemic state compared to the control group.  Results also showed that the Gastric Bypass group experienced greater variation in blood sugar levels after a meal compared to the Duodenal Switch group. The researchers state that this low variability in the Duodenal Switch group is related to high diabetes remission (98%) after surgery. All hypoglycemic events were experienced 30 minutes to four hours after a meal. However, only one-fifth of the hypoglycemic episodes were symptomatic. Thus leading to the conclusion that Gastric Bypass and Duodenal Switch patients experience frequent episodes of non-symptomatic hypoglycemia. Therefore, continued glucose monitoring should be performed to properly evaluate the frequency of these episodes.

Nutritional and Medical Treatments

Patients who experience hypoglycemia due to dumping syndrome respond well to nutritional modifications. Small frequent meals consumed within every 2 to 4 hours for consistent energy intake. A high protein diet is also recommended including foods that are of high biological value such as meat, fish, poultry and low-fat dairy. Avoid the use of simple sugars in the form of juices, jellies, jams, sodas, candies, cookies and cakes.  Increasing fiber in the diet in the form of dark green vegetables and whole grains may slow digestion leading to less rapid emptying into the intestine.  Avoid drinking fluids at meal times. Patients are recommended to wait 30-60 minutes before or after meals. Finally, a relaxed environment is key. Patients should be able to chew their food well and eat slowly to focus on their meal.

Some patients may require medication due to the severity or frequency of their hypoglycemic episodes. Medications such as acarbose and somatostatin have been used for treatment; however nutrition modification is still considered the first choice of intervention.

For patients who experience hyperinsulinemic hypoglycemia, dietary modification and carbohydrate restriction may help with symptoms, however, more aggressive therapies may also be needed. In some cases, removal of a portion of the pancreas (partial pancreatectomy) is performed for significant improvement or resolution of hypoglycemic episodes. In the most extreme case, a reversal of the Bypass may also be required. Overall continuous glucose monitoring is necessary to ensure the patient receives individualized nutritional and medical therapies necessary to improve their symptoms of hypoglycemia.

Medical professionals working with bariatric patients should be aware of the differences between dumping syndrome and hyperinsulinemic hypoglycemia in Gastric Bypass patients in order to provide optimal care.  Regardless of the procedure performed, all bariatric patients should follow up with their surgeon and registered dietitian  for continual care.

References

http://www.diabetes.org/living-with-diabetes/treatment-and-care/blood-glucose-control/hypoglycemia-low-blood.html
http://www.hormone.org/questions-and-answers/2013/nondiabetic-hypoglycemia
http://www.motilitysociety.org/patient/pdf/Dumping%20Diet%205%204b%202006.pdf
Abrahamsson, N., Engstrom, B.E., Sundbom, M., & Karlsson, F. A. (2015). Hypoglycemia in everyday life after gastric bypass and duodenal switch.  European Journal of Endocrinology, 173, 91-100.
Singh, E., & Vella, A. (2012). Hypoglycemia after gastric bypass surgery.  Diabetes Spectrum, 25 (4), 217-221.

ABOUT THE AUTHOR Michelle Paillere, MS, RDN, CDN is a graduate from Long Island University, LIU Post campus.  She completed both her Bachelor’s and Master’s degree in Nutrition at LIU Post. Michelle joined the Northwell Health system at Lenox Hill Hospital in New York as the Practice Dietitian for the Department of Surgery in August 2014. There, she conducts weekly Nutrition classes and leads monthly support groups. Read more articles from Michelle!

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