Older and cheaper pills are just as effective for treating diabetes as some of the more expensive new drugs, researchers report in the Annals of Internal Medicine.

The findings are good news for diabetics who have trouble affording their medication and could further hurt sales of newer and heavily-marketed drugs, such as Avandia.

Researchers, led by Dr. Shari Bolen of Johns Hopkins University in Baltimore, read through 216 published studies and two systematic reviews. Their comparison of 10 diabetes drugs showed they all worked well to reduce levels of glucose in the blood, though each has its drawbacks, the researchers found.

One of the best medications was metformin, sold under the brand name Glucophage and Glumetza as well as generically, for about US$100 a year. It works just as well as other diabetes pills but does not cause weight gain or too-low blood sugar, the analysis found. It also lowers LDL or bad cholesterol.

All the medications carry side effects that patients should carefully consider. For example:

• metformin carried a greater risk for gastrointestinal problems compared with other pills. It also can cause lactic acidosis, the dangerous buildup of lactic acid in the blood.
• repaglinide (sold under the brand name GlucoNorm) was associated with greater risk for hypoglycemia
• sulfonylureas were also associated with greater risk for hypoglycemia. There are three medications in this class sold in Canada: glyburide (sold as a generic and under the brand names DiaBeta and Euglucon), gliclazide (sold as a generic and under the brand names Diamicron and Diamicron MR) and glimepiride (sold under the brand name Amaryl).

And most of the medications, with the exception of metformin, increased body weight by 1 to 5 kg (2 pounds to 12 pounds).

One thing the researchers did not was any evidence to support recent reports that suggest that one of the newer drugs, GlaxoSmithKline Plc's Avandia, might raise the risk of heart attacks.

Consumer Reports Best Buy Drugs also published a consumer guide of the results. Besides metformin, it rates glipizide and glimepiride, sold as Amaryl and Glucotrol, as best bets. Here is a summary of their conclusions, posted on their website:

- Newer drugs are no better. One older type of medicine, the sulfonylureas, and an older drug named metformin work just as well as four newer classes. Indeed, several of the newer drugs are less effective than the older ones.

- Newer drugs are no safer. All diabetes pills have the potential to cause adverse effects, both minor and serious. The drugs' side effect "profiles" may be the most important factor in your choice.

- The newer drugs are more expensive. The newer diabetes medicines cost many times more than the older ones.

- Taking two diabetes drugs can improve blood sugar control. Many people with diabetes do not get enough help from one drug. Two may be necessary. However, taking two drugs can raise the risk of adverse effects and increase costs.

More than 2 million Canadians have diabetes; 90 per cent have Type 2, which typically develops in adulthood and is associated with obesity.