Insulin glargine use and short-term incidence of malignancies—a population-based follow-up study in Sweden

Abstract

In Sweden, during 2006 and 2007, women using insulin glargine alone (no other types of insulin) had an increased incidence rate of breast cancer as compared with women using types of insulin other than insulin glargine. This result may be due to a random fluctuation; the possibilities for examining validity are limited, and no statistically significant results were obtained for any other individual cancer site or for the outcome 'all malignancies'. No definitive conclusions regarding a possible causal relationship between insulin glargine use and the occurrence of malignancies can be drawn from the results of this study.

Does diabetes therapy influence the risk of cancer?

“…This is almost without precedent in the field of cancer [24], and the observation, if confirmed, can only be interpreted in terms of activation or accelerated progression of latent malignant foci. The potential importance of factors that promote cancer progression is suggested by the observation that the rate of clinical prostate cancer is about tenfold greater in the USA than in Japan, whereas the prevalence of latent prostate cancer in autopsy studies is much the same in the two populations [17] (Fig.…”

“…Cancers take many years to develop, and it is therefore surprising that studies such as those reported in this issue of Diabetologia [10,[23][24][25] can claim to detect differences in cancer rates within a few years of exposure to different therapeutic agents. These observations, if confirmed, strongly suggest that the effects we are witnessing arise from differences in the rate of development of pre-existing malignant foci rather than malignant transformation and new cancer cell formation.…”

“…A special advisory group, convened by the EASD, agreed that it would be premature to publish these findings in isolation, and that replication was needed. The three other observational analyses presented in this issue of Diabetologia were therefore commissioned to examine the safety of this insulin [10,24,25], and the main findings will be summarised here. Coincidentally, a further paper in this issue reports a prospective evaluation of the risk of retinopathy progression in patients treated with insulin glargine or human NPH insulin [41].…”

“…Two national diabetes registries in Sweden and Scotland were therefore invited to run their data against those of their respective cancer registries [24,25]. The overall null hypothesis was that patients treated with insulin analogues were not more likely to be diagnosed with cancer during the period of observation.…”

“…Sweden The Swedish study linked data from a number of registries to identify 114,841 patients who received prescriptions for insulin in 2005 [24]. These records were then linked to data from the cancer registry for the two subsequent calendar years.…”