Almost 26 million Americans of all ages now have diabetes and 79 million people have what doctors call “prediabetes.” This is according to 2011 estimates released by the U.S Centers for Disease Control and Prevention on Wednesday.

Prediabetes affects 35 percent of the adult population. According to CDC, it is a condition where blood sugar levels are higher than normal, but it is not high enough to be considered as diabetes. Prediabetes increases a person’s risk for type 2 diabetes, heart disease and stroke.

The large majority of diabetes cases are type 2. This occurs when the cells in the body gradually lose sensitivity to insulin.

Experts believe that weight gain is one major reason why type-2 diabetes is continually rising among Americans. Dr. Christine Resta, an expert on diabetes said that the increasing rates of obesity are linked to the increasing rates of diabetes.

But, another expert said that changes in the way doctors diagnose the illness may have also played a role in the increasing cases of diabetes. This is because American Diabetes Association lowered the guidelines for diabetes diagnosis, said Dr. Jacob Warman, the chief of endocrinology at The Brooklyn Hospital Center in New York City.

The CDC agreed in their report that the shift to hemoglobin A1c testing could help explain for at least some of the increasing numbers. The test measures the sugar levels of a person for a period of two to three months.

The CDC’s National Diabetes Fact Sheet for 2011 also noted that about 27 percent of diabetic Americans, or about 7 million people, still do not know that they have the diseases.