Insulin therapy for type 2 diabetes 'may do more harm than good'

New research has shown that for older patients with type 2 diabetes, the treatment burden of taking drugs to lower blood sugar levels may outweigh the benefits.

Type 2 diabetes occurs when the body does not produce sufficient insulin to function properly, or the body’s cells do not react to insulin. This is known as insulin resistance. The condition causes high blood sugar levels, which over time can cause kidney disease, heart disease, nerve damage and stroke. It is sometimes possible to manage the illness by making changes to diet but often drugs are required to lower blood sugar levels and to reduce the risk of diabetes complications.

However, a new study, carried out by University College London (UCL) in conjunction with the University of Michigan Medical School suggests that the benefits of such treatment, particularly for people over the age of 50, may not always outweigh the disadvantages.

Professor John S. Yudkin from UCL who co-authored the study says: "In many cases, insulin treatment may not do anything to add to the person's quality life expectancy. If people feel that insulin therapy reduces their quality of life by anything more than around 3-4%, this will outweigh any potential benefits gained by treatment in almost anyone with type 2 diabetes over around 50 years old."

The study assessed 5,102 patients in the UK with type 2 diabetes who managed their condition through the use of insulin pills or injections. Over a 20-year follow-up, the researchers looked at how the treatments affected patients' overall quality of life and whether they were effective in reducing their risk of diabetes complications.

They then compared the reduced risk of such complications with the burden of using diabetes medications and the side effects associated with them.

According to the researchers, they found that the benefits of insulin therapy for patients with type 2 diabetes are very much dependent on their age at treatment initiation and the potential side effects, rather than their blood sugar levels.

For example, they estimate that a person with type 2 diabetes who begins insulin therapy at age 45 and lowers their haemoglobin A1c levels by 1% may experience an extra 10 months of healthy life.

But for a patient who starts treatment for type 2 diabetes at age 75, they estimate the therapy may only gain them an additional 3 weeks of healthy life. The researchers say this prompts the question - is 10-15 years of pills or injections with possible side effects worth it?

Prof. Yudkin comments: "Ultimately, the aim of a treatment is not to lower blood sugar for its own sake but to prevent debilitating or deadly complications. If the risk of these complications is suitably low and the burden of treatment correspondingly high, treatment will do more harm than good. The balance between the two can never be defined by a simple figure like blood sugar level."

The team says their findings apply to type 2 diabetes patients with haemoglobin A1c levels below 8.5%. But they note that patients with levels above 8.5% may be likely to see greater benefits from insulin therapy, as they are at greater risk of diabetes complications.

However, the team concludes that using a patient's haemoglobin A1c levels alone to judge whether they will benefit from insulin therapy is a "fundamentally flawed strategy."

"Instead," they add, "each glycaemic treatment decision should be individualised, mostly on the basis of the patients' views of the burdens of therapy, with age and initial level of glycaemic control important secondary considerations."

The study is published in the journal JAMA Internal Medicine.



A fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. Full medical glossary
The basic unit of all living organisms. Full medical glossary
A condition that is linked to, or is a consequence of, another disease or procedure. Full medical glossary
A disorder caused by insufficient or absent production of the hormone insulin by the pancreas, or because the tissues are resistant to the effects. Full medical glossary
The oxygen carrying pigment that is present in red blood cells. Full medical glossary
A hormone produced by the beta cells of the pancreas that acts to lower blood glucose levels. Full medical glossary
A reduced response of the body to the hormone insulin, resulting in raised blood glucose levels. Full medical glossary
One of two bean-shaped organs that are located on either side of the body, below the ribcage. The main role of the kidneys is to filter out waste products from the blood. Full medical glossary
Bundle of fibres that carries information in the form of electrical impulses. Full medical glossary
The ability of a microbe, such as a type of bacteria, to resist the effects of antibiotics or other drugs. Full medical glossary
Any sudden neurological problem caused by a bleed or a clot in a blood vessel. Full medical glossary