title: Impact of cancer diagnosis and treatment on glycaemic control among individuals with colorectal cancer using glucose-lowering drugs.
abstract: OBJECTIVE
  This study aims to evaluate the impact of cancer and its treatment on HbA1c values among individuals with colorectal cancer (CRC) using glucose-lowering drugs (GLDs).
  
  
  METHODS
  Patients with primary CRC (1998-2011) were selected from the Eindhoven Cancer Registry and linked to the PHARMO Database Network including outpatient pharmacy and clinical laboratory data. Patients with more than 2 years of GLDs use prior to cancer diagnosis were included. Linear mixed-effects models were conducted to evaluate changes in HbA1c for colon cancer (CC) and rectal cancer (RC) patients in the 4 years around CRC diagnosis.
  
  
  RESULTS
  Of all CRC patients (n = 4714), 294 (6 %) GLDs users with CC and 144 (3 %) with RC were selected. In the crude model, mean HbA1c at cancer diagnosis was 6.9 % (51.6 mmol/mol) among CC patients and 7.1 % (53.5 mmol/mol) among RC patients. Among CC patients, HbA1c decreased with 0.12 % per year (p = 0.0002) before cancer diagnosis in the adjusted model, and after diagnosis, it increased with 0.12 % per year (p = 0.02). In subgroup analyses, effects on HbA1c were more pronounced in users of anti-anaemic preparations. Among RC patients, HbA1c decreased before diagnosis with 0.18 % per year (p = 0.0006), whereas after diagnosis it changed non-significantly.
  
  
  CONCLUSIONS
  Among users of GLDs, HbA1c decreased with 0.12-0.18 % (1-2 mmol/mol) per year before CRC diagnosis. Only among CC patients, HbA1c increased after diagnosis (0.12 % per year; 1.3 mmol/mol). Modest changes in HbA1c before CRC diagnosis may reflect the effects of an undiagnosed cancer, such as weight loss, anaemia, or the use of anti-anaemic preparations.
authors.affiliation: Netherlands Comprehensive Cancer Organisation, P.O. Box 231, 5600 AE, Eindhoven, The Netherlands. m.zanders@iknl.nl.|Department of Internal Medicine, Máxima Medical Centre, Eindhoven, Veldhoven, The Netherlands. m.zanders@iknl.nl.
authors.forename: Marjolein M J
authors.initials: MM
authors.lastname: Zanders
authors.affiliation: PHARMO Institute for Drug Outcomes Research, Utrecht, The Netherlands.
authors.forename: Myrthe P P
authors.initials: MP
authors.lastname: van Herk-Sukel
authors.affiliation: PHARMO Institute for Drug Outcomes Research, Utrecht, The Netherlands.
authors.forename: Ron M C
authors.initials: RM
authors.lastname: Herings
authors.affiliation: Netherlands Comprehensive Cancer Organisation, P.O. Box 231, 5600 AE, Eindhoven, The Netherlands.|Department of Medical Psychology, CoRPS- Centre of Research on Psychology in Somatic Diseases, Tilburg University, Tilburg, The Netherlands.
authors.forename: Lonneke V
authors.initials: LV
authors.lastname: van de Poll-Franse
authors.affiliation: Department of Internal Medicine, Máxima Medical Centre, Eindhoven, Veldhoven, The Netherlands.|Department of Internal Medicine, Division of General Internal Medicine, Maastricht University Medical Centre+, Maastricht, The Netherlands.|Department of Health Services Research, and CAPHRI School for Public Health and Primary Care, Maastricht University, Maastricht, The Netherlands.
authors.forename: Harm R
authors.initials: HR
authors.lastname: Haak
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000378:metabolism*; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000150:complications* / Q000453:epidemiology / Q000628:therapy; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications* / Q000188:drug therapy / Q000453:epidemiology; D005260:Female; D005858:Germany; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D012042:Registries
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents
keywords: Colorectal cancer; Diabetes mellitus; Glucose-lowering drugs; HbA1c