Caffeine May Hamper Blood Sugar Control
Caffeine at Mealtime May Cause Problems for People With Type 2 Diabetes
July 26, 2004 -- Caffeine may cause problems with blood sugar
control after meals for people with type 2 diabetes, according to a new
Although more research is needed to confirm these results,
researchers say their findings show that people with diabetes who have problems
with glucose and insulin control should consider cutting back on caffeine in
The study showed that after a large dose of caffeine, blood
glucose and insulin levels surge in response after meals in people with type 2
diabetes. These patients can have high insulin levels because they
inefficiently use the hormone to lower blood glucose.
"In a healthy person, glucose is metabolized within an hour
or so after eating. Diabetics, however, do not metabolize glucose as
efficiently," says researcher James D. Lane, PhD, associate research
professor in the department of psychiatry and behavioral sciences at Duke
University, in a news release. "It appears that diabetics who consume
caffeine are likely having a harder time regulating their insulin and glucose
levels than those who don't take caffeine."
"The goal of clinical treatment for diabetes is to keep the
person's blood glucose down," says Lane.
Caffeine May Interfere With Glucose Control
In the study, published in the August issue of Diabetes
Care, researchers looked at the effects of caffeine on glucose and insulin
levels in 14 people with type 2 diabetes who regularly drank coffee. None of
the participants required insulin therapy as part of their diabetes
The participants were observed on two different mornings after
an overnight fast and abstinence from caffeine.
On the observation days, the participants took their prescribed
diabetes medications and provided a blood sample 30 minutes later. While still
fasting they were then given two 125-milligram capsules of caffeine or a
placebo. A cup of coffee contains from 80 milligrams to 175 milligrams of
caffeine. A second set of blood tests were then analyzed an hour after the
taking the pills.
Participants were then fed a liquid meal containing 75 grams of
carbohydrates and another 125-milligram caffeine capsule or placebo. Additional
blood samples were taken an hour and two hours following the meal.
The study showed that caffeine had little effect on glucose and
insulin levels during the fasting period, but it caused significant surges
after eating a meal. People who received the 375-milligram dose of caffeine
experienced a 21% larger increase in glucose levels and a 48% larger increase
in insulin levels compared with those who took the placebo during the two hours
following their meals.
"It seems that caffeine, by further impairing the
metabolism of meals, is something diabetics ought to consider avoiding. Some
people already watch their diet and exercise regularly," says Lane.
"Avoiding caffeine might be another way to better manage their disease. In
fact, it's possible that staying away from caffeine could provide bigger
The researchers say that blood sugars after meals correspond
more closely to overall blood glucose control and may more accurately predict
heart disease risk.