Hypoglycemia after Roux-en-Y surgery for weight reduction

Seven years ago, my patient had a Roux-en-Y procedure to fight her obesity, and the result was just what she wanted — substantial weight reduction and “no more diabetes” as she reported with a huge smile. Her weight had been stable for a few years, and she was comfortable with it. Four months before her office visit, and for reasons she could not explain, she felt the need to go on a weight-reduction diet during which she lost 12 lb. Two months before she was referred to me, she began to experience episodic hypoglycemia. In her early post-surgery period, she had experienced very typical “dumping syndrome” symptoms, but they had finally cleared and the recent episodes of hypoglycemia seemed quite different.

At 10 p.m. one evening, she felt weak and her capillary blood glucose was 50 mg/dL. This was several hours after dinner. Over the next several weeks, she had a CBG of 53 at 7:45 p.m., 59 at 10:30 p.m., 45 at 3:30 p.m., and most worryingly to her, she woke at 1 a.m. one night feeling very unwell and disoriented, and her CBG was 45 mg/dL. She never experienced fasting hypoglycemia.

Physical examination was essentially normal aside from a suggestion of hyper-pigmentation of her abdominal scar and palmar creases. Pulse and blood pressure were normal as were visual fields and the thyroid examination. Her laboratory findings were also all normal, including electrolytes, fasting blood glucose of (89), insulin, C-peptide, cortisol and adrenocorticotropic hormone.

The history had many characteristics of the dumping syndrome, but several pieces of information did not quite fit. Dumping syndrome is not uncommon in the early months after a Roux-en-Y procedure, but patients generally adapt well by taking frequent very small meals, and over time, the syndrome seems to resolve. Additionally, why did the hypoglycemia occur only several hours after a meal and not sooner? She tried several approaches to changing her eating habits, but these episodes persisted.

I discussed this case with my colleague Dr. Anu Puttagunta, who had cared for a patient with much the same history. This late (post-weight-reduction surgery ) and delayed (post-meal) hypoglycemia has been reported,^{1, 2} but the mechanism remains elusive as far as I could tell from my reading. The articles reported that some patients did respond to frequent small meals that had little carbohydrate while others only responded when the diet change was accompanied by acarbose. In some patients, it appears that acarbose alone was sufficient. Dr. Puttagunta’s patient did well with diet modification plus acarbose, so I have begun that same therapy on my patient. She had found those same articles on her own, had modified her diet and had no subsequent episodes of hypoglycemia, but that was not reassuring to her because they were so episodic. When adding the acarbose it was important to remind her to take the tablet (I started with 25 mg three times per day) as soon as she takes her first bite of food. I will report her progress after a few months.

1: Kellogg TA. Surg Obes Relat Dis. 2008;4:492-499. PMID: 18656831.

2: Moreira RO. Obes Surg. 2008;18:1618-1621. PMID: 18566871.