A new study may make you think twice before adding Splenda to your coffee.
Published in the journal Diabetes Care, Washington University School of Medicine in St. Louis researchers found that sucralose, most popularly known by the brand name Splenda, has effects on the body's responses to sugar (glucose) -- which could thereby affect diabetes risk -- despite the fact that it has zero calories.
"Our results indicate that this artificial sweetener is not inert -- it does have an effect," study researcher M. Yanina Pepino, Ph.D., research assistant professor of medicine at the university, said in a statement. "And we need to do more studies to determine whether this observation means long-term use could be harmful."
The new study included 17 people who were severely obese (they had a body mass index over 42; 30 is considered the starting point for obesity) and who didn't regularly consume artificially sweetened products. The study participants drank sucralose or water before taking a glucose challenge test. This test involves drinking a sugary solution before undergoing blood sugar measurements in order to see how well the body responds to sugar; it's typically used as a tool to determine if a woman has gestational diabetes, according to the Mayo Clinic.
After that, the researchers asked all the study participants who first drank water to then drink sucralose before undergoing another glucose challenge test, and all those who first drank sucralose to then drink water before undergoing another glucose challenge test. Researchers found that consuming the sucralose was associated with higher blood sugar peaks and 20 percent higher insulin levels compared with consuming the water, though they noted more studies are needed to determine the actual health effects of a 20 percent increase in insulin.
It's important to understand how exactly insulin and blood sugar play a role in Type 2 diabetes. Insulin is a hormone produced by the pancreas that assists in the absorption of sugar into cells and also helps to decrease the amount of sugar that is circulating in the blood. The amount of insulin secreted into the bloodstream is related to the amount of sugar circulating; when there is less sugar, there is less insulin being secreted, according to the Mayo Clinic. With Type 2 diabetes, cells become insulin-resistant, and the pancreas isn't able to produce enough insulin to get the cells to take up the sugar. When this happens, sugar accumulates in the blood.
The increases in insulin levels in the new study could show that the participants' bodies are able to produce insulin to accommodate the glucose -- or it could be a risk factor for diabetes because when a body is constantly secreting insulin, it raises the risk of cells becoming resistant to the hormone.
But still, even though "we found that sucralose affects the glucose and insulin response to glucose ingestion, we don't know the mechanism responsible," Pepino said in the statement. "We have shown that sucralose is having an effect. In obese people without diabetes, we have shown sucralose is more than just something sweet that you put into your mouth with no other consequences."
Past research in animals has suggested that artificial sweeteners have effects on fasting glucose levels. Particularly, research presented at a 2011 meeting of the American Diabetes Association showed that aspartame -- another kind of artificial sweetener -- is linked with higher fasting glucose levels in mice, TIME reported.
According to Dr. Melina Jampolis, who is an internist and physician nutrition specialist, research in both animals and humans suggests the taste of sweet can boost appetite, and also reinforce cravings for and dependence on sugar. She told HuffPost:
Laboratory and animal studies have found an increase in insulin with some artificial sweeteners, which could drop your blood sugar and make you crave more sugar, but there is no consistent evidence for this in humans. There is some evidence in humans that artificial sweeteners may subjectively increase appetite. However in the context of a meal, it is not known if it causes an increase in hunger and if so, if this outweighs the decrease in calories consumed.
As far as a link between a big source of artificial sweeteners -- diet drinks -- and diabetes, research has been a little more mixed. A study presented at the same American Diabetes Association meeting showed that diet soda-drinkers had dramatically bigger waistlines over a nearly 10-year period, compared with non-diet soda drinkers -- and weight is, of course, a huge risk factor for diabetes.
And a study released earlier this year in the American Journal of Clinical Nutrition showed an association between diet soda and higher Type 2 diabetes risk. That research interestingly showed that while diet and regular soda drinkers had higher Type 2 diabetes risks, those who imbibed with diet had an even higher diabetes risk.
However, a big study in the American Journal of Clinical Nutrition published in 2011 showed that diet sodas actually may not raise diabetes risk, and that the association could be attributed to the fact that people with diabetes or who are obese drink more diet drinks than other people, Reuters reported.
"People who are at risk for diabetes or obesity ... those may be the people who are more likely to choose artificial sweeteners because they may be more likely to be dieting," National Institutes of Health endocrinologist Rebecca Brown, an artificial sweetener researcher who was not involved in the 2011 study, told Reuters.
But still, there's no question that some good old H2O trumps sodas -- diet or not -- to quench thirst and hydrate the body. For some tips on getting more water in your day, click through the slideshow:
Note: This post was updated July 17 to reflect an updated response from Dr. Melina Jampolis on animal and human research on sweeteners.