Answer: A. Nonspecific postprandial symptoms that can be attributed to hypoglycemia are fairly common in patients with a history of gastric bypass. Hypoglycemia is defined as a blood glucose value less than 50 mg/dL. However, many patients may feel symptoms of hypoglycemia before their blood glucose reaches 50 mg/dL.
Postprandial hypoglycemia is thought to be a form of late dumping syndrome. Dumping syndrome in the early stage results in the rapid emptying of the jejunum due to the surgically altered anatomy. In early dumping syndrome, patients have symptoms of flushing, tachycardia, abdominal pain, and diarrhea (typically within 30 minutes of the meal). The late stage of dumping syndrome is a form of “reactive hypoglycemia” (or postprandial hypoglycemia). Typically, this occurs 1 to 3 hours after a meal and is the result of brisk insulin response to hyperglycemia caused by the quick absorption of the simple sugars in carbohydrates in the proximal small intestine.
There is significant controversy regarding the pathophysiology of postprandial hypoglycemia after gastric bypass. Research by Service et al in 2005 suggested that postprandial hypoglycemia could be related to beta-cell hypertrophy and nesidioblastosis. However, additional studies have suggested that while this does occur in a select population of patients after gastric bypass, this is not the cause of postprandial hypoglycemia for most patients. Hypoglycemia after gastric bypass has also been considered the result of altered beta-cell function as well as the result of decreased ghrelin after gastric bypass. Other hypotheses of the cause of postprandial hypoglycemia include complex anatomical changes in the gastrointestinal tract, increased levels of bile acids, or sustained weight loss. Despite the theories regarding the pathophysiology of postprandial hypoglycemia, it remains unknown exactly why some patients develop postprandial hypoglycemia after gastric bypass.