Diabetes Demands a Triad of Treatments
Four classes of oral diabetes drugs are now
available. The oldest class, sulfonylureas (SFUs), act on the pancreatic tissue
to produce insulin. The newest one is Glimepiride, approved by FDA in
Because SFUs can become less effective after
10 or more years of use, other drugs often are needed. Also, there is some
controversy regarding SFUs; some of these agents have been shown in studies to
contribute to increased risk of death from cardiovascular disease.
A newer class is the biguanides, including
Metformin, which was approved by FDA in 1995. This drug acts by lowering cells'
resistance to insulin, a common problem in Type II diabetes.
A third class is the alpha-glucosidase
inhibitors, which include Precose, approved by FDA in 1995, and Miglitol,
approved in 1996. These drugs slow the body's digestion of carbohydrates,
delaying absorption of glucose from the intestines.
In January 1997, FDA approved the first in a
new class of diabetes drugs, Rezulin. The new medicine helps Type II diabetics
make better use of their own insulin by resensitizing body tissues to the
insulin. Parke-Davis, a division of Warner-Lambert of Morris Plains, N.J.,
plans to begin marketing the drug by summer 1997.
"It will be useful in patients who,
despite taking large doses of insulin, still are not achieving adequate glucose
control," Misbin says.
Some oral drugs may be used in combination to
improve blood sugar control. For example, FDA's Misbin says, Metformin, with an
SFU, is particularly useful for Type II diabetics who are obese. "Type II
patients who would ordinarily use (only) SFUs do not gain weight with
Metformin," he explains. "(The combination) also is used for people
taking SFUs but are no longer getting the SFUs' full effect. Studies show that
when you add Metformin to a regimen of an SFU, you get a treatment that is
better than either drug used alone."
Metformin makes users more sensitive to the
body's naturally produced insulin and decreases excessive production of sugar
by the liver, another characteristic of Type II diabetes.
The drugs are not without side effects.
Metformin, for example, can cause serious cramps and diarrhea, and it can't be
used in people with kidney problems. "So if you have to go on this drug,
you need to have kidney function tests," Santiago says.
Metformin is also contraindicated in patients
with liver dysfunction. "It should be used only in healthy patients, and
it's not for the elderly," Misbin says.
Precose is less effective but usually safer
to use than Metformin, he points out. Precose's one major side effect is
flatulence. Precose stops, or delays, absorption of carbohydrates and in doing
so delivers glucose and other carbohydrates, which cause gas, Santiago
explains. "Flatulence can occur when the drug is used at high doses, but
this can be reduced by beginning the drug at a low dose and going up... a
'start-low, go-slow' approach."