How Many Sugary Soda Drinks Will Increase the Risk of Diabetes?

I have railed against sugary sodas (e.g. Coca-Cola) many time on this blog – most recently about the relationship between them and high blood pressure.   Their liability to encourage overweight and obesity is well-known, but a new publication in Diabetes Care has tried to quantify the risk of type 2 diabetes, independently of weight gain.  

Harvard researchers searched medical journals for publications of prospective clinical studies of soda intake and diabetes.  (The metabolic syndrome was also included in this meta-analysis, but I don’t report on that here, as the relevance – even the existence - of the metabolic syndrome is under question.)  There were eight relevant studies comprising 15,043 cases of type 2 diabetes.  These subjects were classified into 4 groups, or quantiles, according to their sugary soda consumption: the lowest quantile (i.e. 25% of subjects) consumed zero or 1 serving/month, and the highest-quantile subjects consumed 1-2 servings/day.

People who drank one or two sugary soda drinks a day were 26% more likely to develop type 2 diabetes, compared with those who hardly ever drank them.  When the researchers excluded 3 studies that controlled for body mass index (BMI) and calorie intake, they found there was a slightly greater association between diabetes and sugar-sweetened drinks.

Before we accept the concept of a direct relationship between cokes and diabetes, we must consider the possibility that sugary-soda intake may reflect generally poor nutritional choices by the subject, e.g. too much saturated fat, not enough fiber.  But 1-2 sodas a day is hardly ‘uncontrolled drinking’.  Sometimes I think the Bloomberg/Nanny State concept of taxing the hell out of sugar-sodas is a good idea.