According to the study, published Tuesday in the Journal of the American Medical Association, up to 14 percent of US adults had diabetes in 2011-2012, and what's even scarier, many of them didn't even know about their condition.
"Diabetes can be treated, but only if it is diagnosed," said lead researcher Catherine Cowie, program director of the division of diabetes, endocrinology and metabolic diseases at the US National Institute of Diabetes and Digestive and Kidney Diseases.
"The medical community needs to be aware that there is a high rate of undiagnosed diabetes in the population."
Most of the people with diabetes tracked by researchers had Type 2 of the disease, the type that generally stems from obesity and inactive lifestyle. Obesity rates typically parallel those of diabetes; a leveling off of the prevalence of obesity also occurred around 2007-2012, the researchers noted.
The number of people with pre-diabetes, characterized by abnormally elevated blood sugar levels that could eventually lead to full-fledged disease without intervention, was especially high in 2012 — making up around 40% of US adults.
Study results were based on US National Health and Nutrition Examination surveys.
Diabetes is a major cause of death in the US, the researchers say, as it increases the risk of heart disease and can cause various complications if left untreated.
Study authors added that people with pre-diabetes can delay or prevent the illness by increasing exercise and making healthier food choices.