Do colorectal cancer resections improve diabetes in long-term survivors? A case-control study.

BACKGROUND: A clinical study was designed that aimed to analyze whether resection of the large bowel in cancer patients might benefit diabetes mellitus.
METHODS: This prospective case-control study included retrospective information. Patients (n = 247) included diabetic and euglycemic groups with colorectal cancer operations (n = 60), cancer gastrectomy (n = 72), exclusive chemoradiotherapy for rectal cancer (n = 46), and noncancer clinical controls (n = 69). Follow-up periods were, respectively, 79.2 ± 27.4, 86.8 ± 25.1, 70.0 ± 26.3, and 85.1 ± 18.2 months (NS). Diabetes groups included patients with prediabetes.
RESULTS: Diabetes remission, defined as conversion from diabetes to prediabetes or from this condition to normal, was documented in, respectively, 32.4 % (11 of 34), 41.2 % (14 of 34), 7.1 % (1 of 14), and 7.7 % (3 of 39) in the four cohorts (P = 0.004). Within the same period, progression of euglycemic participants to diabetes occurred in 30.8 % (8 of 26), 63.2 % (24 of 38), 25.0 (8 of 32), and 20.0 % (6 of 30) (P = 0.028). Diabetes amelioration was associated with weight loss in gastrectomy patients but not in the other groups. Dietary intake, estimated in the two surgical populations, did not predict outcome.
CONCLUSIONS: Diabetes amelioration after colorectal interventions was demonstrated, but progression of euglycemic patients toward prediabetes was not changed in comparison with nonsurgical controls. It is speculated that reshaping of the bowel microbiome or hormone changes after colorectal interventions underlay the improvement in diabetes. Body weight fluctuations could not be incriminated in this investigation.