The artificial sweetener sucralose (Splenda®) is capable of changing the body's insulin response, researchers at Washington University School of Medicine reported in the journal Diabetes Care.
The study included 17 severely obese people who didn't consume artificial sweeteners often and weren't diagnosed with diabetes.
Splenda does have an effect
First author M. Yanina Pepino, PhD, research assistant professor of medicine, said: "Our results indicate that this artificial sweetener is not inert - it does have an effect. And we need to do more studies to determine whether this observation means long-term use could be harmful."
The volunteers were given either water or sucralose to drink before a glucose challenge test, which involved consuming a similar glucose dosage to the amount given as part of glucose-tolerance test.
The researchers wanted to determine whether insulin or blood sugar levels are affected by the combination of sucralose and glucose.
Pepino said that they particularly wanted to study obese people as "these sweeteners frequently are recommended to them as a way to make their diets healthier by limiting calorie intake."
However, it should be noted that artificial sweeteners don't necessarily help limit calorie intake. A previous study by scientists in the US suggested that consuming artificial sweeteners could make people put on weight because experiments on laboratory rats showed that those eating food sweetened with artificial sweeteners ate more calories than their counterparts whose food was sweetened with normal sugar.
The participants were each tested twice. They were first tested after drinkin water followed by glucose, and then after drinking sucralose followed by glucose.
"When study participants drank sucralose, their blood sugar peaked at a higher level than when they drank only water before consuming glucose. Insulin levels also rose about 20 percent higher. So the artificial sweetener was related to an enhanced blood insulin and glucose response."
Pepino said that while the elevated insulin response suggests that a person is able to adjust insulin to spiking glucose levels, it could be detrimental because when people constantly secrete high levels of insulin it can lead to type 2 diabetes.
Artificial sweeteners trigger reactions in receptors on the tongue
Sweeteners react with receptors on the tongue that make people think they are consuming something sweet - even though they contain no calories.
The researchers said that the gastrointestinal tract and the pancreas are capable of detecting sweet foods and drinks and respond by releasing hormones, such as insulin.
The finding indicates that artificial sweeteners may affect metabolism, even at very low doses.
Artificial sweeteners are used in such small quantities that they don't increase calorie intake. However, they react with receptors on the tongue to give people the sensation of tasting something sweet without the calories associated with natural sweeteners, such as table sugar.
Previous studies were limited because they mostly looked at sweetener consumption on its own, Pepino explained. Yet, "in real life, people rarely consume a sweetener by itself. They use it in their coffee or on breakfast cereal or when they want to sweeten some other food they are eating or drinking."
The mechanism by which sucralose influences glucose and insulin levels among obese people is not yet fully understood.
"Although we found that sucralose affects the glucose and insulin response to glucose ingestion, we don't know the mechanism responsible. 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.
What these all mean for daily life scenarios is still unknown, but our findings are stressing the need for more studies. Whether these acute effects of sucralose will influence how our bodies handle sugar in the long term is something we need to know."