MON-134 Use of CGMS for Evaluating Hypoglycemia in Non-Diabetic Patients

Introduction: Continuous Glucose Monitoring System (CGMS), is a tool for measuring blood glucose (BG) levels in patients with Diabetes Mellitus (DM). Post-prandial Hypoglycemia (PPH) is a known complication of Roux-en-Y gastric bypass (RYGB). We present two cases of PPH following RYGB, confirmed by CGMS. Case 1: 70-year-old non-diabetic male, with RYGB 20 yrs. ago, presented with episodes of tremors, generalized weakness and blurring of vision, lasting about 10-15 min, occurring after eating simple carbohydrate foods. Onset and duration of episodes were unclear. In clinic, a POCT BG was 40 mg/dl with symptoms after eating doughnuts prior to the visit. VS- BP 122/58 Sitting, BP 108/57 Standing, P 87/m, Wt. 70.9 kg, BMI 22.mkg/m². Labs: BG 74 mg/dL, Sulphonylurea screen-negative, Cortisol AM 15.4 ug/dL, ACTH 23 pg/mL, C-Peptide 1.31 ng/mL (nl 0.81 - 3.85), Fasting Insulin 4.5 mIU/L (nl 0.0 - 24.9), IGF-I 76 ng/mL (nl 41 - 279), IGF-II 299 ng/mL (nl 267 - 616), BOH-butyrate 0.377 mmol/L (nl 0.020 - 0.270); IA-2 Ab <0.8U/mL (nl <0.8 U/mL). CGMS for 15 days-multiple episodes of PPH. Patient was advised to follow high protein, low carbohydrate diet, later started with Acarbose therapy. CGMS was repeated 3 months later, with marked reductions in PPH. Case 2: 32-year-old male, with RYBG 5 years ago, resulting in 150 lbs. weight loss, presented to clinic for progressive episodes of hypoglycemia. He did not test BG on a regular basis, but when tested occasionally in the morning, reported BG were 90-199 mg/dl, unless he skipped a bedtime snack. Patient reported having one episode when he woke up in the middle of the night “jittery and sweaty,” and BG was 37 mg/dl. His symptoms resolved after juice. He reports not being able to eat large meals and has been eating frequent small meals. He noted symptoms of hypoglycemia, when he eats simple carbohydrates. He also reported some high BG levels (170-180 mg/dl) although he is not previously known to have DM. VS-BP 115/67, HR 67; no orthostasis; Wt 287 lbs, BMI 45. Kg/m². POCT Glucose 64, Fasting Labs: BG 86 mg/dL, HbA1C 5.8%, C-Peptide 1.48 ng/mL, BOH-butyrate 0.7 mmol/L, Cortisol AM 12.2 ug/dL, Insulin Fasting 8.0 mIU/L, Proinsulin 2.4 pmol/L (nl ≤8.0), Insulin Antibody <0.4U/mL (nl 0.0-0.4 U/mL). CGMS for 2 weeks demonstrated repeated PPH and nocturnal hypoglycemia. Diet changes were recommended. Discussion: CGMS compared to blood glucose monitoring, is more efficacious in recording hypoglycemic events, especially if hypoglycemia occurs between testing times, or in usual settings like PPH. Current guidelines recommend use of CGMS in DM patients with hypoglycemic unawareness, nocturnal hypoglycemia, postprandial hyperglycemia. In our cases, CGMS was proven to be effective in diagnosing PPH in RYBG patients. CGMS is also an efficient device to measure therapeutic responses and avoiding hypoglycemia, as well as improving quality of life.