TOPLINE:

Patients with colorectal cancer (CRC) who had diabetes — particularly those with both microvascular and macrovascular complications — were far less likely to undergo major surgical resection and, when operated on, experienced higher postoperative mortality than those without diabetes or those with diabetes but no complications.

METHODOLOGY:

• Researchers analysed real-world data of 372,477 patients diagnosed with a first primary CRC in England between January 2011 and December 2021 to assess how the risk for adverse outcomes varies by diabetes status and related complications.
• Preexisting diabetes was identified using standard diagnostic codes recorded during inpatient stays within 6 years before the diagnosis of CRC; 11.8% of patients had preexisting diabetes.
• Patients were grouped on the basis of their diabetes-related complication status: no diabetes; diabetes without complications; diabetes with microvascular complications (retinopathy, nephropathy, and neuropathy); diabetes with macrovascular complications (cardiovascular, cerebrovascular, and peripheral vascular disease); and diabetes with both microvascular and macrovascular complications.
• Outcomes assessed were 5-year survival (measured from the date of major surgical resection for those who had surgery or from diagnosis for those who did not), 90-day postoperative mortality, in-hospital death, unplanned readmission within 30 days, and prolonged length of stay (≥ 21 days).

TAKEAWAY:

• Only 34% of patients with both microvascular and macrovascular complications vs 60.2% of those without diabetes and 61.7% of those with diabetes but no complications underwent potentially curative major surgical resection.
• Among patients who underwent a major surgical resection, 5-year survival declined stepwise with greater complication severity compared with no diabetes: Hazard ratios (HRs) for mortality were 1.36 for microvascular complications, 1.48 for macrovascular complications, and 1.90 for combined complications (P < .001 for all).
• Likewise, the risk for 90-day postoperative mortality was more than double for those with combined complications vs those without diabetes (odds ratio, 2.18; 95% CI, 1.90-2.51); rates of unplanned 30-day readmission, in-hospital death, and prolonged length of stay also rose progressively with complication severity.
• Among patients who did not undergo major surgical resection, the risk for mortality also increased with complication severity, peaking in those with combined complications compared with those without diabetes (HR, 1.28; P < .001).

IN PRACTICE:

"In conclusion, this study demonstrates that the risk of adverse outcomes in patients with diabetes and CRC is heterogeneous. Reduction in overall survival is influenced by the presence of diabetes complications and related to complication load, with the highest risk observed in those with both microvascular and macrovascular disease," the authors wrote.

SOURCE:

This study was led by Rebecca J. Birch, University of Leeds, Leeds, England. It was published online on March 23, 2026, in Diabetic Medicine.

LIMITATIONS:

Diabetes status and complication data were based solely on secondary care records. Complications were identified from inpatient records in the 6 years before the diagnosis of CRC, likely capturing mainly advanced hospitalisation-requiring conditions while overlooking earlier or milder cases. Patient characteristics varied across complication subgroups, with those having combined complications being older and from more socioeconomically deprived areas.

DISCLOSURES:

This study was supported by Cancer Research UK and Yorkshire Cancer Research, with partial support received from the Leeds National Institute for Health and Care Research (NIHR) Biomedical Research Centre and the Oxford NIHR Biomedical Research Centre. The authors disclosed having no relevant conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.