Treatments to reduce blood sugar levels do more harm than good in many type 2 diabetes patients, particularly older people, finds new research from UCL, the University of Michigan and the Ann Arbor Veterans Affairs Hospital
The study, published in JAMA Internal Medicine, found that for many people the benefits of taking diabetes medications are so small that they are outweighed by the minor harms and risks associated with treatment. The benefits of treatment decline with age and by age 75 the harms of most treatments are likely to outweigh any potential benefits.
3.2 million people in the UK have been diagnosed with type 2 diabetes. More than 250,000 inject insulin every year and approximately 850,000 receive the oral diabetes medication metformin.
Whether patients will benefit from a diabetes treatment depends less on their blood sugar level than their age and the hassles and side-effects of the treatment, say the authors.
They modelled the net gains or losses to quality of life associated with treatments to lower blood sugar, based primarily on a twenty-year study of type 2 diabetes treatments involving 5,102 people in the UK. Additional impacts on quality of life were calculated from published medical evidence on the burden, safety and efficacy of different treatments.
Type 2 diabetes is typically diagnosed with a blood test that measures levels of haemoglobin A1c in the blood, which indicates average blood sugar level over the last three months. In the UK, people with an A1c above 6.5% can be diagnosed with diabetes although patients at highest risk have an A1c above 8.5%.
''In many cases, insulin treatment may not do anything to add to the person's quality life expectancy,'' says John S Yudkin, Emeritus Professor of Medicine at UCL, co-author of the latest paper. ''If people feel that insulin therapy reduces their quality of life by anything more than around 3 -4 per cent, this will outweigh any potential benefits gained by treatment in almost anyone with type 2 diabetes over around 50 years old.''
The researchers looked at how effective diabetes treatments were at preventing associated diabetes complications, such as kidney, eye and heart disease. They compared the reduced the risk of such complications with the increased risk of side-effects and the burden of taking pills or injections.
''Ultimately, the aim of a treatment is not to lower blood sugar for its own sake but to prevent debilitating or deadly complications,'' explains Professor Yudkin. ''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.
''A typical person with type 2 diabetes who begins treatment at age 45 and reduces their A1c by 1 e cent may gain up to 10 months of healthy life. At age 75, they may gain as little as 3 weeks of healthy life. Whether this is worth 10-15 years of pills and injections with potential side-effects is ultimately up to the patient.''
The study applies to the majority of type 2 diabetes patients with A1c levels below around 8.5 per cent. However the benefits of treatment are likely to be greater in those patients – maybe one third – with very high blood sugar levels.
''For people with type 2 diabetes, managing blood sugar levels is crucial to preventing associated diabetes complications, such as kidney, eye and heart disease, but the question is how low do levels need to be?'' says lead author Sandeep Vijan, Professor of Internal Medicine at the U-M Medical School and research scientist at the Center for Clinical Management Research at the VA Ann Arbor Healthcare System.
''If you're having low blood sugars, gaining weight or find frequent insulin shots to be disruptive to your daily life – all for minimal health benefits – the drugs are doing more harm than good. Prescribing medicine isn't just about reducing risks of complications, but also about helping patients live well and have an overall high quality of life.''