Study ‘provides reassurance’ to insulin-dependent type 2 diabetes patients
medwireNews: A study based on the UK Clinical Practice Research Datalink suggests that taking insulin does not increase the risk for mortality among patients with type 2 diabetes.
Similar to previous research, John-Michael Gamble (Memorial University of Newfoundland, St John’s, Canada) and team initially found a link between insulin dose and mortality after accounting for baseline variables.
During a median follow-up of 3.1 years of 6072 adults with type 2 diabetes who had newly started insulin therapy, the mortality rate varied from 46 per 1000 person–years during periods of exposure to less than 25 units per day to 32 per 1000 person–years for periods of exposure to 100 units or more.
Accounting for baseline confounders – including gender, duration of diabetes treatment, body mass index, and comorbidities – reversed this trend, with mortality risk being increased between 1.41- and 2.16-fold during exposure to insulin doses of at least 25 units compared with lower doses.
But the association lost significance after further adjustments that included changes over time in glycemic control, bodyweight, hypoglycemic events, and occurrence of cardiovascular events, the researchers report in The Lancet Diabetes & Endocrinology.
The author of an accompanying commentary, Amanda Adler (Addenbrooke's Hospital, Cambridge, UK), agrees that the analysis used (marginal structural models) is a major strength of the study, but adds that it depends on “assuming no unmeasured confounding, and, alas, this is not empirically verifiable.”
She adds that, despite the relationship being negative, most hazard ratios for insulin doses of 25 units and above were greater than 1.0, implying that “a bigger study would find significant associations suggesting harm, but also that residual confounding would remain.”
Adler concludes: “Only when confounding does not interfere and the study is big enough, can one [confidently] conclude that insulin is not harmful to people with type 2 diabetes.
“Crucially, when this occurs, one could also wonder why more insulin does not make people with type 2 diabetes live any longer.”
medwireNews is an independent medical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2016