Mortality after cancer among patients with diabetes mellitus: effect of diabetes duration and treatment

Abstract

Aims/hypothesis The prognostic role of different diabetes treatment types has not been studied in detail. We compared mortality rates among cancer patients with and without diabetes, accounting for diabetes treatment and diabetes duration. Methods This register-based study included all cancer patients diagnosed in Denmark during 1995-2009. The patients were classified into four groups according to diabetes status at the time of cancer diagnosis: no diabetes, diabetes without medication, diabetes with only oral hypoglycaemic agent (OHA) or diabetes with insulin treatment. Poisson models were used to examine the association between pre-existing diabetes in cancer patients and mortality relative to the nondiabetic cancer population. Results Among 426,129 patients with incident cancer, we identified 42,205 patients with diabetes prior to cancer diagnosis. Overall, cancer patients with diabetes had higher mortality rates than non-diabetic cancer patients, highest among OHA-or insulin-treated patients. For all cancers combined and diabetes duration of 2 years at cancer diagnosis, insulintreated patients experienced the highest mortality rate ratios starting from 3.7 (95% CI 2.7, 5.1) for men and 4.4 (3.1, 6.5) for women 1 year after cancer diagnosis, increasing to 5 (3.5, 7.0) for men and 6.5 (4.2, 9.3) for women 9 years after cancer diagnosis. Conclusions/interpretation Our study provides strong evidence that cancer patients with pre-existing diabetes experience higher mortality than cancer patients without diabetes. The higher mortality seen among cancer patients treated with OHAs or insulin is in accordance with the existing evidence that more intensive diabetes treatment reflects a larger degree of comorbidity at the time of cancer diagnosis, and hence poorer survival.

Life years lost associated with diabetes: An individually matched cohort study using the U.S. National Health Interview Survey data

“…13.9 years for black females vs. 7.7 years for black males [7]. It has also been reported that cancer patients with diabetes experience higher mortality than cancer patients without diabetes [25] consistent with our findings. In this study, diabetes shortened the median survival age by 20 years among patients with pre-existing CVD, which was higher than that among patients without CVD even though hazard ratios for those with and without CVD were similar.…”

Mortality after cancer among patients with diabetes mellitus: effect of diabetes duration and treatment: (questionable) classification of diabetic patients based on combination of specific glucose-lowering drugs. Reply to Holden SE, Bannister CA, Currie CJ [letter]

“…To the Editor: In the light of the general comments made about our article [1] by Holden et al [2], we acknowledge that we did not specify with sufficient emphasis that our study was based on the entire population of cancer patients in Denmark, that is to say, it was essentially demographic in its nature.…”

“…& The classification of patients is unequivocal: '…patients with diabetes but no history of glucose-lowering medication (DM NoMed; n=15,453), patients exclusively treated with oral hypoglycaemic agents (OHAs) (DM+OHA; n=17,708), or patients on insulin (DM+Ins; n=9,044)' [1]. The patients receiving glucagon-like peptide 1 (GLP-1) are included in the OHA group; however, the number of cancer patients treated with GLP-1 is negligible.…”

Mortality after cancer among patients with diabetes mellitus: effect of diabetes duration and treatment: (questionable) classification of diabetic patients based on combination of specific glucose-lowering drugs

“…To the Editor: We read the article by Ranc and colleagues with interest [1]; however, we have concerns about its value. This large-scale study investigated the differences in survival following incident cancer in people with and without diabetes, accounting for diabetes treatment and diabetes duration.…”

“…

Abbreviation

OHA Oral hypoglycaemic agentTo the Editor: We read the article by Ranc and colleagues with interest [1]; however, we have concerns about its value. This large-scale study investigated the differences in survival following incident cancer in people with and without diabetes, accounting for diabetes treatment and diabetes duration.

Whilst the National Diabetes Register has the advantage of providing nationwide data for the whole of Denmark, the lack of information on specific diabetes treatments and diabetes type is a major limitation of this study.

…”