Treatment of Hypoglycemia Following Gastric Bypass Surgery

Roux-en-Y gastric bypass (RYGB) is one of the most commonly performed bariatric procedures used in the treatment of severe obesity. RYGB has in several studies been shown to result in significant and sustained weight loss. Moreover, RYGB has a beneficial effect on obese subjects with type 2 diabetes by improving blood glucose regulation, resulting in remission or partial remission of type 2 diabetes already days after surgery.

The changes of the anatomy of the stomach and small intestine cause a faster and more abrupt increase in blood glucose after a meal. As a consequence of the changed glucose absorption after RYGB and the increased insulin secretion, some subjects experience the condition named postprandial hyperinsulinemic hypoglycemia. Postprandial hyperinsulinemic hypoglycemia is typically seen years after RYGB and the symptoms vary from mild dizziness to confusion, loss of consciousness and seizures. The condition is characterized by large postprandial blood glucose variations accompanied by exaggerated insulin and glucagon-like peptide 1 (GLP-1) responses. Continuous glucose monitoring (CGM) have shown that subjects suffering from postprandial hyperinsulinemic hypoglycemia presents large variations in blood glucose from values below 3.5 mmol/L to diabetic values above 11.1 mmol/L within the first hour after a meal.

At present, there are no treatment guidelines beside dietary recommendations. Experimental treatment includes diet modifications, pharmaceutical treatments and surgical procedures. Several pharmaceutical agents have been attempted in the management of postprandial hyperinsulinemic hypoglycemia, but overall the existing studies consist of few case reports and case series evaluated primarily by relief of symptoms and not by CGM and hormonal analyses.

The study is designed as a randomized, non-blinded cross-over study including five treatment arms. The pharmaceutical agents are: a) Glucobay, b) Januvia, c) Verapamil, d) Victoza and e) Signifor. The treatment duration is 1 - 3 weeks, except for Signifor, which is administered for one day only. Each treatment period is separated by a wash out period of 7-10 days.

Sixteen none diabetic women are included in the study. They have undergone RYGB and have symptoms of postprandial hyperinsulinemic hypoglycemia. Moreover, former CGM has shown fluctuations in blood glucose of more than 5 mmol/L during daily living and with at least one blood glucose reading below 3.5 mmol/L.

Six days continuous glucose monitoring will be performed at run-in and during each treatment arm, except for e) Signifor due to the short treatment period. At the end of the CGM measurement a meal tolerance test (MTT) will be performed. During the MTT blood samples for glucose measurements and hormone assessments (insulin, C-peptide, GLP-1, gastric inhibitory peptide (GIP), glucagon, insulin like growth factor (IGF-1), epinephrine, norepinephrine) will be drawn continuously as well as continuous pulse recording and blood pressure measurements.

Inclusion criteria

• symptoms of postprandial hyperinsulinemic hypoglycemia.
• fluctuations in blood glucose of more than 5 mmol/L during daily living
• at least one blood glucose reading below 3.5 mmol/L.
• More than 18 months since RYGB
• HbA1c < 40 mmol/L
• Hemoglobin > 7,3 mmol/L
• Ferritin > 30 µg/L
• Cobalamin > 150 picomol/L
• Creatinine < 105 mmol/L
• C peptide > 1,0 nmol/L
• Insulin > 35 pmol/L
• Normal EKG
• Negative human chorionic gonadotropin (hCG) urine test
• Females of reproductive age: use of safe contraception

Exclusion criteria

• Treatment for cardiovascular disease
• Treatment with antipsychotics, antidepressants or anxiolytics
• Smoking
• Treatment for thyroid disease
• Prior medical treatment of postprandial hyperinsulinemic hypoglycemia
• Allergy for the study medicine