A new study published in the journal JAMA Internal Medicine suggests that for older patients with type 2 diabetes, medications to lower blood sugar levels may "do more harm than good."

Approximately 25.8 million people in the US have diabetes, with type 2 diabetes accounting for 90-95% of all cases.

Type 2 diabetes is characterized by insulin resistance - the inability of the body to produce enough insulin or use the hormone effectively, which causes high blood sugar levels. Over time, high blood sugar levels can cause kidney, eye or heart diseases, nerve damage or stroke.

Diagnosis of type 2 diabetes is usually determined through a blood test that measures hemoglobin A1c levels in the blood. This test reveals the average level of glucose the patient has had in their blood over the past 3 months.

In the US, type 2 diabetes is diagnosed when hemoglobin A1c levels reach 6.5% or higher. The higher A1c levels are, the greater the risk of other health problems.

Sometimes the condition can be managed through changes in diet, but other patients with type 2 diabetes may need medication - such as insulin or metformin - to help lower their blood sugar levels, and ultimately, reduce the risk of diabetes complications.

But the researchers of this latest study, from University College London (UCL) in the UK, the University of Michigan Medical School and the Ann Arbor Veterans Affairs Hospital, MI, claim that the benefits of such treatment - particularly for people over the age of 50 - may not always outweigh the negatives.

"In many cases, insulin treatment may not do anything to add to the person's quality life expectancy," says study co-author John S. Yudkin, emeritus professor of medicine at UCL. "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."

Benefits 'dependent on age at treatment initiation and side effects'

For their study, led by Sandeep Vijan, professor of internal medicine at the University of Michigan Medical School, the team assessed 5,102 patients in the UK with type 2 diabetes who managed their condition through the use of insulin pills or injections.

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Researchers say 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.

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 hemoglobin 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 hemoglobin 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 hemoglobin A1c levels alone to judge whether they will benefit from insulin therapy is a "fundamentally flawed strategy."

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

"Currently, we are failing our patients by not recognizing that their preferences and views of treatment burden are the most important factors in helping them make glycemic treatment decisions that are best for them."

Earlier this year, Medical News Today reported on a study published in the journal PLOS One, in which researchers took to Mount Everest in order to show how hypoxia - low oxygen levels in the body - is associated with development of type 2 diabetes.