Progression occurs more slowly in patients at the low end of the new, wider range for IFG.
In 2003, an expert committee recommended that the threshold for defining impaired fasting glucose (IFG) be lowered from 110 mg/dL to 100 mg/dL. The new threshold has been widely adopted, and the range for IFG is now defined as 100–125 mg/dL. This study from an Oregon HMO examined the rate of progression from newly acquired IFG to overt diabetes using the new and old IFG criteria.
Researchers identified 5452 nondiabetic people with at least two fasting plasma glucose (FPG) levels in the 100–125 mg/dL range and a documented FPG less than 100 mg/dL preceding the first elevated level. During an average follow-up of about 6 years, the rate of progression to overt diabetes was 1.3% per year among those whose first abnormal FPG was 100–109 mg/dL. In contrast, the rate of progression was 5.6% per year among those whose first abnormal FPG was 110–125 mg/dL.
Comment: Many patients have been labeled with the diagnosis of impaired fasting glucose since the 100 mg/dL threshold was adopted. As expected, this study illustrates that progression from IFG to overt diabetes occurs more quickly from the range of 110–125 mg/dL than from the range of 100–109 mg/dL. Clinicians may find this study's findings helpful when they discuss the implications of IFG with newly diagnosed patients. A key unanswered question is whether expanding the pool of patients with IFG will lead to better long-term health outcomes.
— Allan S. Brett, MD
Published in Journal Watch General Medicine March 1, 2007
Nichols GA et al. Progression from newly acquired impaired fasting glucose to type 2 diabetes. Diabetes Care 2007 Feb; 30:228-33.