Examining the UK Clinical Practice Research Datalink (CPRD) - data that characterises about 10% of the UK population - a team of researchers from Cardiff University's School of Medicine looked at the risk of death for patients taking insulin compared with other treatments designed to lower blood glucose levels in people with type 2 diabetes.
The team's epidemiological study found people have greater risk of individual complications associated with diabetes such as heart attack, stroke, eye complications and renal disease when compared with patients treated with alternative glucose-lowering treatments.
"Insulin treatment remains the most longstanding blood-glucose-lowering therapies for people with type 2 diabetes, with its use growing markedly in recent years," according to Professor Craig Currie from Cardiff University's School of Medicine, who led the study.
"However, with new diabetes therapies and treatments emerging there has been a new spotlight on treatments to ensure what the best and safest form of diabetes treatment is.
"By reviewing data from CPRD between 1999 and 2011 we've confirmed there are increased health risks for patients with type 2 diabetes who take insulin to manage their condition," he adds.
The study adds to previous findings which identified potential health risks of insulin in this specific group of people.
Initial concerns were first raised regarding the use of insulin in type 2 diabetes from a population-based study in Canada, which reported a three-fold increase in mortality.
A similar study of people in UK primary care with type 2 diabetes treated with insulin also reported a 50% risk of increased mortality compared with another common treatment regimen.
Professor Currie adds: "Patients currently being treated with insulin should not, under any circumstances, stop taking their medications, and it is important to emphasise that this report related to only type 2 diabetes which typically starts in older people who are overweight.
"Each patient's individual circumstances are different and treatment decisions are managed by their clinician with all of their medical history fully considered.
"The vast majority of people who take insulin will experience no adverse effects and it remains a reliable and common form of treatment worldwide but this study shows that we need to investigate this matter urgently and the drug regulatory authorities should take interest in this issue.
"Anyone who is concerned should speak to their GP first before taking any action on managing their condition."
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Mortality and Other Important Diabetes-Related Outcomes With Insulin vs Other Antihyperglycemic Therapies in Type 2 Diabetes was published in The Journal of Clinical Endocrinology and Metabolism.