Do Soft Drinks Cause Diabetes?

While some wellness experts will admit, reluctantly, that sugar does not cause diabetes (all by itself) they will positively jump all over soft drinks, telling you, among all the other evil attributes of soda, that it will give you diabetes. In fact, you may even hear the sugar-free diet soda will give you diabetes.

Why is it that people are saying this? If consumption of sugar, absent other dietary and lifestyle factors (total carbohydrate intake, exercise, etc.) doesn’t cause diabetes, then why should sugary soft drinks do so? Is it something else about soft drinks that leads to type 2 diabetes?

How Do We Know Sugar Doesn’t Cause Diabetes?

The question to ask is how do we know that sugar doesn’t cause it? First, what we mean by sugar are the simple mono and disaccharide sugars. To keep it simple, think table sugar and corn syrup. But honey and any other simple sugar count. For more, see the simple sugar guide. We do not know that the excess consumption of these does not cause diabetes from experiments. You can’t experiment on people in that way, and certainly, to do so for a long enough period of time would be prohibitive even if it were ethical. We know that sugar does not cause diabetes from observational studies, in which large groups of people have been followed closely for years. They get a medical checkup to establish a baseline, their dietary habits are recorded, and then they are followed for many years, from five to twenty. Enough of these types of studies have shown no association between total sugar intake and risk of developing diabetes. And some studies show a negative association! In other words, sugar consumption, in those studies, was associated with less risk for developing type 2 diabetes.

The Fructose Exception

However, one sugar, fructose, is an exception. Two studies have shown no association (like usual) but two others have shown a positive association. To be clear, this is not enough to go maligning fructose and declaring it the cause of diabetes. The evidence is mixed, but even if it were not, this type of evidence would not be enough, by itself. I’ll get to that.

How Could Sugar Soft Drinks Cause Diabetes if Sugar Does Not?

The problem with soft drinks is that observational studies have shown at least some association between excess consumption of sugary soft drinks and risk of developing type 2 diabetes. Excessive, in these studies, is usually consdered more than two 12-ounce soft drinks a day. And, even more surprising is that diet soft drinks also show this positive association.

But these are not randomized controlled trials. They cannot prove a cause and effect relationship between soda drinking and development of diabetes. The problem is that such studies cannot rule out other lifestyle factors that may tend to accompany a soft drink habit. After all, what do people eat along with those soft drinks? Potato chips. Candy. Other carb-loaded snacks. And, do people who drink more soft drinks also drink more alcohol? What else? Do they exercise less? Do they have a bad diet in general?

There is something else to consider. What if the people in this study who contributed to these results were already developing diabetes and had higher than normal blood glucose levels? A symptom of diabetes is being thirsty all the time. Could it be that they reached for that cold can of Coke more often to quench their thirst, thinking nothing of it? Could it be that what many people would see as causality, drinking soft drink causing diabetes, was the reverse? Diabetes caused them to drink more sodas? It is possible. And before you say, well, they should have drunk water, they may have. If you were thirsty all the time would you drink only water? Or would you also turn to sugary beverages when you got tired of plain water? It may be unlikely, but until any of these factors can be ruled out, we cannot say that soft drinks cause diabetes. 1

While these types of studies can make one hit the pause button on soft drinks and any number of things, there is also plenty of similar evidence that, if you combine an overall healthy diet with regular exercise you can either prevent type 2 diabetes or, if you are especially fated to it because of genetic inheritance, delay it for quite a while. And the reverse is certainly true. A long-term poor diet combined with a lack of physical activity greatly increases the chances of developing diabetes.

There is at least some indication that even among studies that showed a positive association between sugar soft-drink consumption and diabetes risk, this risk was somewhat attenuated by adjusting for BMI (body-mass index). In other words, when body weight was considered, being overweight coincided with an increased risk. 2

Diabetes Can Often Be Prevented

What is an overall healthy diet? Well, that is beyond the reach of this article and really, not the purview of this site. There are plenty of good sources on healthy eating, but the ones who tell you that you must completely deprive yourself are probably trying to sell you something. A healthy diet is one with a variety of healthy foods but with less overall calories. Such a diet can include a moderate consumption of junk food. Keep in mind that excessive amounts of sugar or carbohydrates, in general, can cause weight gain, and being overweight is one factor that can increase your risk of diabetes. Sugar-sweetened soft drinks are the major source of excess calories for Americans. 3 So, yes, if you drink a lot of soda, switching to water or beverages with fewer calories could lead to weight loss, even without exercise. However, the same would be true of a high-fat diet if you cut down on your fat intake.

My take? If you maintain, for the most part, a healthy lifestyle, then soft drinks are probably not at all likely to increase your personal risk of diabetes. And, the same is true of any particular food or beverage. The same is also, of course, true of sugar. If you truly have an increased risk of diabetes, it is not because you put some extra sugar in your coffee each morning.

More information:

American Diabetes Association – Are You At Risk? https://www.diabetes.org/newsroom/press-releases/2015/are-you-at-risk-for-type-2-diabetes.html