Major clinical trials, most notably Cleveland Clinic’s STAMPEDE (Surgical Therapy and Medications Potentially Eradicate Diabetes Efficiently), have demonstrated that Roux-en-Y gastric bypass surgery improves glycemic control in insulin-requiring patients with type 2 diabetes (T2D), even resulting in remission in many cases months to years after surgery. However, the perioperative insulin dose needed in this population had not been well studied — until now.

Cleveland Clinic researchers recently presented the results of a retrospective study comparing pre- and post-operative insulin regimens and dosages in patients with T2D who had undergone gastric bypass during a four-year period. The study, presented as an abstract and eposter at the recently concluded American Association of Clinical Endocrinologists (AACE) 25^th Annual Scientific & Clinical Congress,¹ found that on average, patients required an 86 percent post-operative reduction in their total daily dose of insulin within two days of surgery.

“Our study results demonstrated the drastic insulin dose reduction needed immediately after bariatric surgery, which will hopefully help guide inpatient diabetes management in this population,” says M. Cecilia Lansang, MD, MPH, director of Cleveland Clinic’s Inpatient Diabetes Service and chair of the Diabetes Care Committee.

The study was driven by nurse practitioner leaders, who recognized the challenges related to glycemic control following bariatric surgery, especially on post-op days one and two. “Since there aren’t any guidelines right now to treat post-bariatric surgery patients with insulin, everyone was looking at blood glucose [BG] levels on a case-by-case level and using common sense — but we knew that more specific data would help us treat these patients better,” says study co-author Danielle Diemer, MSN, RN, FNP-C. “Our motivating factor in conducting this study was that patients are going through a major life change, and we want their BG to be well controlled post-operatively for optimal outcomes.”

The first-of-its-kind analysis has set the stage for future randomized controlled trials, with an ultimate goal of driving the development of much-needed clinical guidelines in this area, Diemer says.

Study Highlights

The study included retrospective chart reviews of 114 adult patients with T2D who were insulin-requiring (with or without non-insulin agents), who underwent Roux-en-Y surgery from 2010-2014. Patient demographics included: 55 percent female, 75 percent Caucasian and average age 52.8 years. The average BMI was 46.2 kg/m², and most common comorbidities included hypertension (89 percent), lipid disorders (82 percent) and sleep apnea (75 percent).

The average length of stay following surgery was 2.5 days. Researchers compared BG levels and insulin doses for the following time points: before surgery not on a liquid diet, the day prior to surgery on a liquid diet, day of surgery, post-op day one, and post-op day two.

“Most patients were managed on insulin alone post-operatively, consistent with recommendations for inpatient diabetes management,” Diemer says.

The analysis found that:

• Mean glycemic control on post-op days one and two (while on a liquid diet) was fair, falling in the upper end of the American Diabetes Association (ADA) guidelines of 100-180 mg/dL in hospitalized patients.
• The entire cohort had an 86 percent reduction in total daily dose of insulin, or a weight-based dose of 0.09 unit/kg/day by post-op day two.
• A subgroup analysis performed on patients with BG levels of 100-140 mg/dL for >50 percent of the time on post-op day two found that their insulin dose reduction requirement was even greater, at 95 percent.

Overall, researchers observed that patients required an 85 to 95 percent insulin dose reduction post-operatively compared with home doses in order to keep BG in the upper range of ADA goals.

“The No. 1 take-home message is that in most cases, dosages need to be hugely reduced immediately following gastric bypass,” says Karen Terry, DNP, RN, NP-C, GNP-BC, another of the study’s co-authors. “Not only is it important to be cognizant of that for inpatient diabetes management, but it’s also crucial to recognize that these patients won’t be going back home on high doses of insulin.”

Reference

1. Diemer D, Matthews M, Terry K, Romich E, Saran H, Lansang C. Post-operative insulin requirements in bariatric surgery. ePoster presented at: American Association of Clinical Endocrinologists (AACE) 25th Annual Scientific & Clinical Congress; May 25-29, 2016; Orlando, FL.