Preoperative insulin therapy as a marker for type 2 diabetes remission in obese patients after bariatric surgery

Background: Obesity not only increases the chances of developing diabetes—one of the top causes of death in the United States—but it also results in further medical complications. Objective: To compare the 6-month and 1-year postoperative remission rates of type 2 diabetic (T2D) patients after bariatric surgery based on preoperative glycosylated hemoglobin (A1C) stratification and pharmacologic therapy: insulin-dependent diabetic (IDD) versus noninsulin-dependent diabetic (NIDD). Setting: Academic hospital, United States. Methods: We retrospectively analyzed a prospectively maintained database of 186 obese patients with a diagnosis T2D who had undergone either a sleeve gastrectomy or a Roux-en-Y gastric bypass surgery at our hospital. Results: At 6 months (n = 180), patients who were stratified by preoperative A1C levels (<6.5; ≥6.5 to<8; ≥8) had 70.5%, 51.7%, and 30.0% remission rates (P<.001) and at 1 year (n = 118) patients had 72.0%, 54.0%, and 42.8% remission rates (P =.053), respectively. When patients were substratified by preoperative pharmacologic therapy, IDD and NIDD patients had different remission rates within the same A1C level. At 6-months follow-up within A1C ≥6.5 to<8 (IDD versus NIDD), the remission rate was 23.5% versus 64.1% (odds ratio [OR]:.173, confidence interval [CI]:.0471,.6308, P =.0079), and within A1C ≥8 the remission was 24.0% versus 37.5% (OR:.5263, CI:.2115, 1.3096, P =.1676), respectively. At 1-year follow-up within A1C ≥6.5 to<8, the remission rate was 30.0% versus 62.9% (OR:.2521, CI:.0529, 1.2019, P =.0838), and within A1C ≥8 the remission was 31.4% versus 61.9% (OR:.2821, CI:.0908,.8762, P =.0286), respectively. Furthermore, when IDD patients were compared between A1C ≥6.5 to<8 and A1C ≥8 the remission rates were nearly identical, and for NIDD patients A1C was not significantly associated with remission regardless of the level, except at 6 months. Conclusion: While a difference was observed between overall A1C levels—the lower the A1C level, the higher the remission rate—IDD patients had lower remission rates than NIDD patients irrespective of A1C levels; further, IDD patients performed similarly across A1C levels.