The Effect of Glucomannan Soluble Fiber on Glucose Homeostasis in Patients With Roux En Y (RNY) Gastric Bypass Surgery

One of the emerging complications of RNY gastric bypass surgery is mild to severe refractory/ recurrent postprandial hypoglycemia. This complication can lead to a significant reduction in quality of life to severe disability. Unfortunately at this time there are no treatment guidelines or proven therapeutic options for the treatment of this complication. One of the proposed treatment options is the use of fiber supplements to help modify the absorption of glucose, slow the food bolus transit time more toward normal and restore the postprandial (after meal) glucose homeostasis. The investigators are proposing a pilot project for the use of Glucomannan soluble fiber as a treatment option for postprandial hypoglycemia in this cohort. This project will help the investigators to identify if Glucomannan soluble fiber can be used as an effective dietary supplement to eliminate or reduce this condition

Currently there are no therapeutic guidelines and no proven therapy available to reduce hypoglycemic episodes post RNY gastric bypass. A study done in 1988 (n=8/ patients with partial gastrectomy and hypoglycemia) showed improvement in plasma glucose level and peak insulin response in patients suffering from this complication and who were given Glucomannan soluble fiber with a standard meal. Glucomannan is a natural, odorless soluble fiber that is found in the konjac plant. The konjac glucomannan is the most viscosity food gum in nature. It has about ten times the viscosity than the cornstarch. Unfortunately no further studies have been done so far to validate or support this therapy in patients with RNY gastric bypass. This study will be the first one to see effectiveness of Glucomannan, exclusively in patients who are post RNY gastric bypass and have a diagnosis of postprandial hypoglycemia.

Visit 1: consent and screening bloodwork: Thyroid Stimulating Hormone (TSH), Free T4, Cortisol, Creatinine, and Insulin-like Growth Factor (IGF)

Visit 2: iPro Continuous glucose monitor (CGM) device will be placed and will be worn for next 5 days. The subjects will maintain a diet history and will be given a One Touch glucometer and strips to check their blood glucose at home four times a day for next five days and log this onto the System Patient Log (included).

Subjects will undergo a mixed meal tolerance test (MMTT), a, which includes consumption of a after a standard meal (Boost) and scheduled blood draws over 3 hours.

Visit 3: The subject will return to the research coordinator for the iPRO® Continuous Glucose Monitor (CGM) removal and data download from the device. After physical exam and vital sign measurement, a new iPro® CGM device will be placed and will be worn for next 5 days. The subjects will maintain a diet history and will be given a One Touch glucometer and strips to check their blood glucose at home four times a day for next five days and log this onto the System Patient Log (included)

Subjects will undergo a MMTT, which includes consumption of a after a standard meal (Boost) + 5 grams of Glucomannan soluble fiber powder and scheduled blood draws over 3 hours.

For the next five days subjects will take 5 grams (1 teaspoon) of Glucomannan soluble fiber (provided by the investigator) three times a day with meals.

Visit 4: The subject will return to see the research coordinator for the CGM removal and data download from the device. At this time the study is completed.

Eligibility Criteria:
Inclusion Criteria:

1. Age: \>18 year
2. Have undergone RNY Gastric Bypass \>1 year.
3. Have symptoms of hypoglycemia (altered mental status or level of consciousness, with or without seizure, palpitations, tremor, anxiety/arousal, sweating, hunger, paresthesias, behavioral changes, fatigue, confusion), documented hypoglycemia (blood glucose\<70 mg/dl), hypoglycemic unawareness (recurrent hypoglycemia without symptoms).

Exclusion Criteria:

1. Patient with Diabetes Type 1 or Type 2. Information identified during history taking or subject undergoing treatment of active diabetes.
2. Patient on medications or treatment (insulin, metformin, glyburide, diazoxide, octreotide, calcium channel blockers), which can cause hypoglycemia.
3. Patients with disorders, which can cause hypoglycemia, like untreated hypothyroidism, adrenal insufficiency, and growth hormone deficiency.
4. Complications of RNY i.e. Ulcers and hernia.
5. Current use of glucocorticoids or medications known to affect blood glucose levels.
6. Any patient that is unable to comply with dietary recommendations, technical iPro, glucometer actions or any part of the research protocol