Equity of Cancer and Diabetes Co-Occurrence: A National Study With 44 Million Person-Years of Follow-Up

The co-occurrence of diabetes and cancer is becoming increasingly common, and this is likely to compound existing inequities in outcomes from both conditions within populations. METHODS: In this study, we investigate the co-occurrence of cancer and diabetes by ethnic groups in New Zealand. National-level diabetes and cancer data on nearly five million individuals over 44 million person-years were used to describe the rate of cancer in a national prevalent cohort of peoples with diabetes versus those without diabetes, by ethnic group (Māori, Pacific, South Asian, Other Asian, and European peoples). RESULTS: The rate of cancer was greater for those with diabetes regardless of ethnic group (age-adjusted rate ratios, Māori, 1.37; 95% CI, 1.33 to 1.42; Pacific, 1.35; 95% CI, 1.28 to 1.43; South Asian, 1.23; 95% CI, 1.12 to 1.36; Other Asian, 1.31; 95% CI, 1.21 to 1.43; European, 1.29; 95% CI, 1.27 to 1.31). Māori had the highest rate of diabetes and cancer co-occurrence. Rates of GI, endocrine, and obesity-related cancers comprised a bulk of the excess cancers occurring among Māori and Pacific peoples with diabetes. CONCLUSION: Our observations reinforce the need for the primordial prevention of risk factors that are shared between diabetes and cancer. Also, the commonality of diabetes and cancer co-occurrence, particularly for Māori, reinforces the need for a multidisciplinary, joined-up approach to the detection and care of both conditions. Given the disproportionate burden of diabetes and those cancers that share risk factors with diabetes, action in these areas is likely to reduce ethnic inequities in outcomes from both conditions.