IMPORTANCE Patients with medically complex conditions undergoing repair of large or recurrent hernia of the abdominal wall are at risk for early postoperative hyperglycemia, which may serve as an early warning for delays in recovery and for adverse outcomes. OBJECTIVE To evaluate postoperative serum glucose level as a predictor of outcome after open ventral hernia repair in patients with major medical comorbidities. DESIGN, SETTING, AND PARTICIPANTS We performed a retrospective medical record review of 172 consecutive patients who underwent open ventral hernia repair at Penn State Milton S. Hershey Medical Center, an academic tertiary referral center, from May 1, 2011, through November 30, 2013. We initially identified patients by medical complexity and repair requiring a length of stay of longer than 1 day. MAIN OUTCOMES AND MEASURES Postoperative recovery variables, including time to the first solid meal, length of stay, total costs of hospitalization, and surgical site occurrence. RESULTS Postoperative serum glucose values were available for 136 patients (79.1%), with 130 (95.6%) obtained within 48 hours of surgery. Among these patients, Ventral Hernia Working Group grade distributions included 8 patients with grade 1, 79 with grade 2, 41 with grade 3, and 8 with grade 4. Fifty-four patients (39.7%) had a postoperative glucose level of at least 140 mg/dL, and 69 patients (50.7%) required insulin administration. Both outcomes were associated with delays in the interval to the first solid meal (glucose level, Ն140 vs <140 mg/dL: mean [SD] delay, 6.4 [5.3] vs 5.6 [8.2] days; P = .01; Ն2 insulin events vs <2: 6.5 [5.5] vs 5.4 [8.4] days; P = .02); increased length of stay (glucose level, Ն140 vs <140 mg/dL: mean [SD], 8.0 [6.0] vs 6.9 [8.2] days; P = .008; Ն2 insulin events vs <2: 8.3 [6.1] vs 6.5 [8.4] days; P < .001); increased costs of hospitalization (glucose level, Ն140 vs <140 mg/dL: mean [SD], $31 307 [$20 875] vs $22 508 [$22 531]; P < .001; Ն2 insulin events vs <2: $31 943 [$22 224] vs $20 651 [$20 917]; P < .001); and possibly increased likelihood of surgical site occurrence (glucose level, Ն140 vs <140 mg/dL: 37.5% [21 of 56 patients] vs 22.5% [18 of 80 patients]; P = .06; Ն2 insulin events vs <2: 36.4% [24 of 66 patients] vs 21.4% [15 of 70 patients]; P = .06). Not all patients with diabetes mellitus developed postoperative hyperglycemia or needed more intense insulin therapy; however, 46.4% of the patients who developed postoperative hyperglycemia were not previously known to have diabetes mellitus, although most had at least 1 clinical risk factor for a prediabetic condition. CONCLUSIONS AND RELEVANCE Postoperative hyperglycemia was associated with outcomes in patients in this study who underwent complex ventral hernia repair and may serve as a suitable target for screening, benchmarking, and intervention in patient groups with major comorbidities.