Does Eating Too Much Sugar Lead To Diabetes?

A spoonful of sugarThere are many misconceptions regarding the causes of diabetes. One of these is that excessive sugar intake leads to the development of type-2 diabetes. The general scientific consensus is that sucrose (table sugar) itself doesn’t cause diabetes although products with added sugar are typically calorie dense and therefore may contribute to the development of obesity if consumed to excess. Therefore, providing that an individual is a healthy weight, moderate consumption of foods rich in sucrose, or any other sugars, is unlikely to increase that individuals risk of developing diabetes.

Being overweight or obese risk the strongest risk factor for type-2 diabetes with an estimated PAR (population attributable risk) of 70%. This means that 70% of diabetics have developed the disease as a result of their excess weight. Other risk factors for diabetes include a sedentary lifestyle, a diet high in saturated fat, and a low intake of fiber. Although many studies have looked at patterns of sugar intake and the risk of diabetes, the majority of these studies have found no link between sugar and diabetes, independent of BMI.

One of the largest studies on the issue of sugar intake and diabetes risk was published in the journal Diabetes Care in 2003 and involved 38,480 women aged 45 and older who were followed up for an average of 5.8 years. Participants filed out a food frequency questionnaire at the beginning of the study so that sugar intake could be estimated. Over the course of the study, 918 cases of diabetes occurred. The researchers found no link between diabetes and fructose, sucrose, glucose, lactose, or total sugar intake. In fact, in the fully adjusted model, which controlled for BMI, smoking, alcohol intake, exercise, and a number of other potential confounders, sucrose intake actually showed a weak negative association with diabetes risk although the link was not statistically significant.

Another interesting finding from the study was that those in the highest quintile for sucrose intake, who averaged 57.2g per day, actually had a slightly lower BMI than those in the lowest quintile who averaged 25.8g of sucrose per day.

One of the limitations of the study is that the authors did not discriminate between sugars that were naturally present in foods, and sugar that was added to processed foods.

A second study, published in the journal Diabetes in 2006, looked at the effects of a low sucrose (10% of total energy), and high sucrose (25% of total energy) diet on a group of 14 healthy men who consumed each diet for 6 weeks. The researchers found to significant differences in insulin sensitivity, fasting plasma glucose, serum insulin, and interstitial glucose levels between the high and low sucrose diets although a slight increase in LDL and total cholesterol was observed following the high sucrose diet. The researchers concluded that: “These results suggest that important pathogenic processes that precede diabetes and vascular disease are not significantly worsened by sucrose itself”.

On the other hand, a 2004 study looked at how intake of sugar sweetened beverages influenced weight gain and diabetes risk in a cohort of young and middle aged women. The researchers found that women who increased their soft drink consumption over the study period showed increased weight gain compared to women who had decreased their soft drink consumption. Sugar sweetened soft drink consumption was also linked to diabetes with those consuming more than 1 drink a day 83% more likely to develop diabetes than those averaging less than 1 sugar-sweetened soft drink a month. Adjusting the results for BMI reduced the risk to 39% meaning that much of the excess risk of diabetes was due to higher BMI levels in regular consumers of soft drinks. Interestingly, consumption of fruit juice was not associated with an increased risk of diabetes.

The researchers noted that because of the low satiety of sugar sweetened beverages, people don’t fully compensate for the calories they consume through sugary soft drinks by reducing their subsequent intake of solid foods. This results in an overall increase in energy intake which can lead to weight gain and therefore the development of diabetes.

There is also some evidence that a diet consisting predominantly of foods with a high glycemic index can lead to impaired glucose tolerance and an increased risk of diabetes. Even in this regard, sucrose actually has a relatively moderate glyecmic index compared to many carbohydrate rich foods such as white bread, white rice, and potatoes. White bread for example has a GI of 72 and mashed potatoes a GI of 80 compared to 65 for sucrose. This means that substitution of sucrose with processed, starchy carbohydrates could actually cause much more significant fluctuations in blood sugar levels, potentially raising the risk of developing impaired glucose tolerance and eventually diabetes.

To sum up, consumption of sucrose and other sugars do not appear to be a significant contributor to diabetes risk, providing that a healthy weight is being maintained. Sucrose that is found naturally in whole foods is obviously more desirable than sugar that is added to processed foods because it tends to come with fibre and a variety of vitamins and minerals. Processed foods containing sugar tend to be calorie dense, but deficient in beneficial nutrients. Individuals who struggle to maintain a healthy weight should avoid sugar sweetened beverages in particular because they are linked with excess energy intake and subsequent weight gain.