Author	V.L.Z. Gordon-Dseagu
Author	J. Mindell
Author	N. Shelton
Author	J. Head
Author	D. Hochhauser
Author	M. Marmot
Abstract	Background Studies which have sought to explore the associations between diabetes and cancer have produced heterogeneous results and there is a paucity of evidence related to glycated haemoglobin (HbA1c) and cancer risk. Methods Initial analyses utilised data from the Health Survey for England (HSE) and SHeS combined linked to mortality and Cancer Registry data (n=204,533, including 7,199 with diabetes) to explore the associations between diabetes, HbA1c and cancer incidence and mortality. Additional analyses used linked Whitehall I data (n= 19,019, including 237 with diabetes). Odds Ratios (ORs), Hazard Ratios and 95% Confidence Intervals (CI) were estimated adjusted for a range of confounding factors using logistic, multinomial and Cox regression. Results 18,310 deaths occurred within the HSE/SHeS follow-up period (4,997 from cancer). The adjusted OR for cancer among those with diabetes was 1.27, CI 1.12-1.43. Raised HbA1c was associated with an excess risk of dying/developing cancer; diabetes and HbA1c were associated with a number of site-specific cancers. When analyses were stratified by cardiovascular disease (CVD) baseline status, only those with diabetes who did not report CVD had a statistically significant excess in cancer mortality (adjusted OR: 1.27, 1.08-1.48). There were also sex differences in cancer incidence and mortality risk. 81% of Whitehall I participants died during follow-up (including 4,076 from cancer). These results did not replicate the initial analyses in finding no association between diabetes and cancer mortality -this is likely to relate to the age of the two cohorts and the differences in CVD mortality and incidence. Conclusion The association of diabetes and HbA1c with increased cancer incidence and mortality was not consistent across studies or population groups. Differences in risk by sex and CVD status suggest the need for health professionals to tailor services to take account of the individual circumstances of their diabetic patients.