Level 2: Mid-level evidence
A recent observational study evaluated the malignancy rates associated with human insulin and insulin analog in 127,031 adults with diabetes receiving first-time insulin monotherapy (Diabetologia. 2009;52:1732-1744). All participants were without known malignant disease at baseline; 75% were treated with human insulin and 19% with insulin glargine exclusively. Others received either insulin aspart or insulin lispro. In mean follow-up of 1.6 years, 5,009 patients developed malignancies; there was a dose-dependent association with malignancy rate found for all insulin types. Insulin glargine was associated with a greater increase in cancer risk compared with human insulin in dose-adjusted analysis.
The American Diabetes Association (ADA) has issued a statement advising patients not to stop taking insulin glargine (available online at www.diabetes.org/diabetesnewsarticle.jsp?storyId=20358264&filename=20090626 /comtex20090626iw00001849KEYWORDMissingEDIT.xml, accessed September 14, 2009).