POSTOPERATIVE INSULIN REQUIREMENTS IN BARIATRIC SURGERY.

OBJECTIVE: Though insulin dose reduction months after surgery is a well-studied outcome, there are limited data on immediate postoperative changes. The goals of the present study were to ( 1) To determine peri-operative glycemic control in patients with type 2 diabetes mellitus (DM) on insulin who have undergone Roux-en-Y gastric bypass (RYGB) and ( 2) to compare pre- and postoperative insulin regimens and dosages in these patients.

METHODS: A retrospective chart review was conducted on patients with type 2 DM on insulin who underwent RYGB surgery. Blood glucose (BG) levels and insulin doses were compared prior to surgery, on the day of surgery (DOS), and postoperative days (POD) 1 and 2. Subgroup analysis was performed to see if insulin dose was related to glucose control.

RESULTS: There were 114 subjects with a mean (SD) age of 52.8 ± 9.8 years, body mass index (BMI) 46.2 ± 8.0 kg/m2 , glycated hemoglobin A1c (HbA1c) 8.3% (67 mmol/mol) ± 1.7%, and 66% on insulin plus noninsulin medications and 34% on insulin only. Mean blood glucose (BG) significantly decreased from the DOS (185 ± 43 mg/dL) through POD2 (160 ± 36, P<.0001). The median daily insulin dose significantly decreased from before surgery on usual diet (75 units [36, 116 interquartile range (IQR)]) through POD2 (6 [2, 15 IQR]), P<.0001). The median insulin dose per body weight decreased significantly from before surgery on usual diet (0.58 units/kg [0.35, 0.84 IQR]) through POD2 (0.04 [0.02, 0.11 IQR]), P<.0001). The subgroup with relatively good control experienced a larger percentage reduction in insulin requirements versus subjects with poor control.

CONCLUSION: An 87.5% reduction in total daily insulin dose was seen by POD2. This will assist in developing algorithms for insulin titration postbariatric surgery.

ABBREVIATIONS: BG = blood glucose DM = diabetes mellitus DOS = day of surgery HbA1c = glycated hemoglobin IQR = interquartile range IV = intravenous NPH = neutral protamine Hagedorn POD = postoperative day RYGB = Roux-en-Y gastric bypass SSRI = sliding scale regular insulin.