SAT-718 - Predicting the Plunge: CGM-Driven Nutrition Adjustments Prevent Hypoglycemia after Bariatric Surgery

Introduction
Hypoglycemia is an increasingly recognized complication of bariatric surgery. It has
been described in the literature as late dumping syndrome, reactive hypoglycemia, or
post-prandial hyperinsulinemic hypoglycemia. The underlying mechanisms involve
altered anatomy post-surgery and its effects on the transit time of food. Although
continuous glucose monitoring has revolutionized the care of diabetic patients, its
potential use in tracking glycemic patterns and predicting hypoglycemia in patients
after bariatric surgery remains under-recognized. Here, we describe a case in which
CGM enabled the patient to identify impending hypoglycemia and appropriately time
meals.
Case Discussion
A 32-year-old female with a past medical history significant for asthma, anxiety, and
Roux-en-Y gastric bypass surgery presented to the internal medicine clinic with
recurrent episodes of hypoglycemia. She underwent bariatric surgery 5 years ago and
had been experiencing symptomatic hypoglycemia for 4 weeks. The patient had been
consuming small portions of low-glycemic-index carbohydrates with every meal, in
addition to adequate protein. However, she continued to experience symptomatic
hypoglycemia at least three times a week, prompting ED visits. The symptoms included
lightheadedness, tremors, diaphoresis, and syncope. Hypoglycemia typically occurred
1–3 hours after meals.
The patient was evaluated by bariatric surgery and started on acarbose to delay
digestion of carbohydrates, but she was unable to tolerate it due to excessive bloating.
Laboratory workup revealed normal fasting glucose and insulin levels. MRI of the
abdomen did not reveal any evidence of insulinoma. A provocative test—the oral
glucose tolerance test—to evaluate for meal-induced hypoglycemia was also positive
and aided in the diagnosis of post-prandial hyperinsulinemic hypoglycemia. The patient
was provided with a continuous glucose monitor to track real-time glycemic patterns
and appropriately time meals/snacks. Additionally, she maintained a hypoglycemia
diary to document the severity and frequency of episodes. Follow-up visits 8 weeks later
revealed a significant decrease in the frequency of hypoglycemic episodes—from
approximately three episodes per week to no more than two per month.
Discussion
This case highlights the use of CGM as an adjunctive tool in managing post-bariatricsurgery
hypoglycemia. It enables patients to track glucose trends, identify impending
hypoglycemia, and time meals accordingly. It also provides a more patient-centered
and individualized approach and offers a reasonable alternative when pharmacological
options are limited or may worsen pre-existing gastrointestinal symptoms.

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