ATLANTA, Ga. (CNN) — Drinking two or more sweetened drinks per day could greatly increase your risk of diabetes, according to new research.
In fact, it could double it.
In the study, two or more 200-milliliter servings of sweetened drinks, consumed daily, were found to double the risk of developing the condition. Given that standard 12-ounce drink cans are more than 300-milliliters, this means just 1 1/2 of these drinks per day could double your risk.
But more importantly, the level of risk was about the same regardless of whether the drinks used sugar or artificial sweeteners. So choosing the diet option may make no difference, as both types were seen to result in two times the risk of having diabetes.
"Not all studies have been able to look at sugary and artificially (sweetened) beverages separately," said Josefin Edwall Löfvenborg, a nutritionist at the Karolinska Institutet in Sweden, "(but) it's getting more and more established that soft drinks increase risk of Type 2 diabetes."
Different levels of risk
As well as finding that two servings of sweetened drinks doubled the risk of diabetes among participants, the team also found that drinking more than five 200-milliliter servings per day resulted in 10 times more risk of developing Type 2 diabetes, when compared against people who didn't consume any sweetened drinks.
"We wanted to see the effect of larger intakes than two," said Löfvenborg.
However, the sample size for people drinking this much sugar or artificial sweetener was smaller.
"Not many people had such high an intake, so the numbers are less reliable," she said.
But a separate analysis also found an incremental increase in risk per sweetened drink, particularly for developing Type 2 diabetes. For each serving of a sweetened beverage — artificial or not — the risk of Type 2 diabetes was found to increase by 20 percent.
Löfvenborg highlighted that as general levels of data available on artificially sweetened drinks is smaller, she thinks more evidence of this kind is needed.
"We need more data on artificially sweetened drinks before we (advise) anything," she said.
The many forms of diabetes
Using data from more than 2,800 people included in a Swedish population study, Löfvenborg and her team looked at the amount people reported drinking of sweetened beverages in questionnaires among groups with Type 2 diabetes, latent autoimmune diabetes (LADA) and a control group with no forms of the condition.
LADA is a form of slow progressing autoimmune diabetes that occurs in adults, similar to Type 1 diabetes, where the pancreas cannot produce enough insulin and some experts consider it a hybrid of Type 1 and Type 2 diabetes.
"We wanted to investigate this type of diabetes, because not much is known," said Löfvenborg.
Type 1 diabetes is an autoimmune disease where the cells in the pancreas that produce insulin are destroyed, and is typically diagnosed in children and young adults, whereas Type 2 diabetes is related to lifestyle factors and causes the body to become resistant to insulin. LADA sits between the two.
LADA is not routinely diagnosed, said Löfvenborg, as it requires extra testing to identify autoimmunity, so "it's hard to estimate the prevalence," she said. It is estimated that 9 percent of Type 2 diabetes diagnosed among Europeans would be positive for autoimmunity resembling LADA.
Based on the data available, the consumption of sweetened drinks — using sugar or artificial sweetener — showed these proportional links to increased risks of diabetes in both forms.
More than 29 million people were reported to have diabetes in the US in 2012 and globally 415 million people had the condition in 2015.
Why does this happen?
The underlying biology behind this increase in risk is not fully understood, but Löfvenborg has some theories, including that the increased calorie intake from these drinks increase the likelihood of obesity, which is a risk factor for diabetes.
But in terms of developing autoimmunity to cause LADA, she thinks this might be because sweetened drinks cause a spike in sugar levels, and therefore, insulin levels to control it. Excessive spikes might then stress and "wear out the cells" that produce insulin, she said.
Another hypothesis is that these spikes make people less sensitive to insulin over time.
"There's probably more than one mechanism behind this," she said.
Other key factors involved
"A most interesting finding was that the higher risk was the same for both sweetened and artificially sweetened beverages, suggesting that greater risk of diabetes was not directly related to higher calorie intake, or adverse metabolic effects of sugar (in the form of sucrose) from the sweetened drinks," Christine Williams, professor of human nutrition at the University of Reading in the UK, said in a statement. She was not involved in the research.
"The study suffers from the same limitations as apply to most association studies. Even after controlling for effects of many other possible factors, including poor diet and heavier body weight, it is not possible to conclude that sweetened beverages are the direct cause of the relationship they have shown."
European soft drinks association, UNESDA, agreed that many factors are to blame.
"The conclusion that this study draws is that people who are overweight and lead unhealthier lifestyles are more at risk of developing diabetes," said UNESDA communications manager Sam Rowe. "Type 2 diabetes is the result of many factors including family history and lifestyle factors such as overweight, unhealthy diet and physical inactivity ... academics need to consider the wide range of causes rather than attempt to attribute blame to one product."
Williams added a further caveat for the people diagnosed with diabetes.
"The well-known problem of under reporting (subjects self-reporting lower intakes of foods they know to be less healthy) is known to be more common in overweight and obese individuals. The diabetic subjects in this study were heavier than the control subjects."
Dr. Elizabeth Robertson, director of research at Diabetes UK, agreed with these limitations. "Participants who drank more sweetened drinks also led unhealthier lifestyles in general, meaning a number of other factors like diet and exercise may have affected the results."
"More research is needed to determine the relationship between sweetened drinks and the risk of developing LADA and Type 2 diabetes," she said.
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