Avandia, a drug used by millions of diabetes patients, may contribute to bone loss, according to a new study conducted in mice.
Experts fear that, over the long term, rosiglitazone (Avandia) may speed osteoporosis, the thinning of the bones that can lead to dangerous and even fatal fractures.
Background
Avandia and four other diabetes drugs from the same class were given a "black box" warn
(FDA). That warning advises users of an increased risk of heart failure while on the drug The black box message is the FDA's strongest label warning.
With an estimated 3.5 million or more US patients taking Avandia, the public health impact from the point of view of both heart failure and bone degradation could be substantial, experts say.
The Study
Avandia affects a key cellular protein called the peroxisome proliferator-activated receptor (PPAR-gamma). In their study, the California team discovered that, in mice, activating this receptor also stimulates the production of osteoclasts, cells whose key function is to degrade bone.
Proper bone health is maintained by a balance between osteoclasts and osteoblasts, the cells that build bone up. If either side is out of whack, so to speak, bones become thinner, more fragile and prone to fracture.
The current results are particularly disturbing in light of prior studies, the experts said.
"It was previously known that Avandia mediates bone loss by inhibiting bone formation," explained study senior author Ron Evans, PhD, a professor at the Salk Institute for Biological Studies in La Jolla, California. "Our work identified an additional mechanism, in which Avandia promotes bone resorption. These are the two parts of the checks-and-balance system that maintains bone in good shape. The drug weakens both sides of the balance mechanism, leading to an increased risk for osteoporosis."
"Previous research showed that Avandia reduced osteoblasts," added Paul Brandt, PhD, an associate professor of neuroscience and experimental therapeutics at Texas A&M Health Science Center College of Medicine, in College Station. "Combine the two, and you're going to get thinning of the bone."
Recommendations
"Our study suggests that long-term rosiglitazone usage in the treatment of type 2 diabetes may cause osteoporosis due to both increased bone resorption and decreased bone formation," said Evans. "Because Avandia is effective in controlling glucose and restoring the body's sensitivity to insulin, we do not recommend that people stop their treatment. You must balance the benefits against the complications."
"Anyone who is already at risk for osteoporotic fractures should consider an alternative anti-diabetic drug," added Dr. Brandt. "There are many alternatives," he said." It may also be possible to blunt some of Avandia's effects with anti-osteoporosis drugs such as bisphosphonates, raloxifene, vitamin D and calcium."
Better Insulin Therapy
In a recent five-year study, researchers followed I 1,300 diabetes patients who received insulin therapy using either syringes to inject insulin extracted from a vial...or insulin pens, which contain a needle and a premeasured dose of the drug. The insulin pen group had average annual health care costs nearly $17,000 lower than those who used syringes (due to lower total hospital costs, for example, and fewer trips to emergency rooms).
Theory: When using an insulin pen, there is less risk of getting an incorrect dose. If you use a syringe for insulin therapy: Ask your doctor if switching to an insulin pen would be appropriate for you.
Diabetes and Hip Fracture
In a recent analysis of 16 studies involving 1 836,941 people, researchers found that people with diabetes were 70% more likely to fracture a hip than nondiabetics. The reason has not yet been determined.
If you have diabetes: Ask your doctor if you should have an annual bone density test.
Diabetics, Examine Your Feet!
People with diabetes are prone to foot problems that can be serious enough to require amputation. Good hygiene and regular inspection of the feet can help catch potential problems early.
Here are suggestions on how to care for feet and prevent injury, courtesy of the US National Diabetes Information Clearinghouse…
- Wash feet thoroughly each day in warm—not hot water.
- Make sure to dry them completely after washing
- Gently file down corns and calluses with a pumice stone after washing feet.
- Inspect feet every day, looking for blisters, calluses, cuts, sores or any signs of redness.
- Apply lotion to dry skin—but never between the toes.
- Cut toenails regularly, and file the edges with an emery board.
- Avoid walking barefoot, make sure shoes fit well, and always wear socks or stockings with shoes.
In an 18-month study, 225 people with diabetes inspected their feet daily for signs of diabetes-related ulcers. One group also used a TempTouch thermometer (a probe is placed against the bottom of the foot).
Result: Patients who used the thermometer were three times less likely to develop ulcers than those who only visually examined their feet.
Theory: A wound heats up before the surrounding skin breaks down, providing an early warning of infection.
If you have diabetes: Ask your doctor if you should use a TempTouch, available with a prescription for about $150.
Warning: Selenium Can Raise Diabetes Risk
In a recent study about the effects of supplemental selenium, almost 5% of people taking 200 micrograms (mcg) of selenium daily developed type 2 diabetes, compared with 3% who develop the disease after using a placebo. Selenium has been promoted for improving glucose metabolism, but the new study suggests that it could be dangerous, not helpful. Most people get enough selenium from their diets to meet the Recommended Dietary Allowance of 55 mcg/day. It's best to avoid selenium supplements, even in multivitamins.
Poor Hearing for Older Diabetics
Older people who have diabetes have poorer hearing than people the same age who don't have diabetes. In people age 60 and older with type 2 diabetes, high blood sugar may cause tiny blood vessels in the inner ear to break, disrupting sound reception.
Self-defense: If you have type 2 diabetes, have your hearing tested regularly and wear hearing protection (earplugs, earmuffs, etc.) in all noisy situations—mowing the lawn, using power tools, attending concerts.
