Diabetes drugs may sometimes do more harm than good
02 July 2014 by Clare Wilson
New Scientist, Magazine issue 2976.
"FIRST do no harm" is the maxim that doctors try to live by. For people with type 2 diabetes, this could require a rethink of the treatment they receive.
The side effects of diabetes drugs mean that taking them could be counterproductive for people with only slightly raised blood sugar, a study has found. The researchers conclude that doctors should stop automatically recommending drugs for the two-thirds of diabetics who fall into this category. Instead, people should be able to decide for themselves if they think treatment is worth it. The downsides particularly outweigh the benefits for older people.
Type 2 diabetes often occurs in people who are overweight, as their bodies stop responding properly to insulin. Blood sugar levels can skyrocket as a result. People with the condition are more likely to have heart attacks, kidney damage and blindness.
If insulin function can't be restored by weight loss and exercise, doctors prescribe a drug called metformin. If this doesn't lower blood sugar sufficiently, insulin injections and drugs called incretins are also prescribed.
Metformin's side effects tend to be mild and temporary but insulin and incretins can cause more dangerous problems such as "hypos", when blood sugar drops too low. In severe cases, people can fall into a coma.
Despite this, doctors have increasingly prescribed insulin and incretins over the past decade, reflecting the consensus that blood sugar levels should be kept under tight control.
However, there is little evidence that such control prevents the health problems linked with diabetes. One trial showed the approach reduced heart attacks but the participants were younger than a typical person with diabetes. Three trials involving relatively older people showed no benefits. One even found the approach increased deaths.
Sandeep Vijan at the University of Michigan, Ann Arbor, and his colleagues used data from those trials, and others, to model the net gains or losses to people's quality of life. Their model shows that a 45-year-old with slightly raised blood sugar on drug treatment would gain up to 10 months of healthy life. A 75-year-old would gain only three weeks (JAMA Internal Medicine, DOI: 10.1001/jamainternmed.2014.2894).
Age matters because the chance of an older person, with perhaps five years of life ahead of them, developing complications from diabetes is lower than that of a younger person with, say, 35 years. So older people get less benefit from the drugs, but all the downsides. "The person best able to decide whether [the extra weeks or months] are worth years of pills and injections is the patient," says co-author John Yudkin of University College London.
The latest study will change clinical practice, predicts Richard Lehman, a family doctor in Banbury, UK.