The growing prevalence of prediabetes and diabetes remains a growing health concern. Diagnosis is often based on elevated plasma fasting glucose (PFG), glycated haemoglobin (HbA1c) levels, or the oral glucose tolerance test. PFG refers the amount of glucose in the bloodstream following a meal or period of fasting, elevated levels of which are indicative impaired glucose metabolism.
Using CGM devices, Smadar Shilo, Weizmann Institute of Science, Rehovot, Israel, and colleagues investigated the daily fluctuations in PFG levels in non-diabetic individuals. In brief, CGM data, using the FreeStyle Libre Pro Flash (Abbott Laboratories, Green Oaks, Illinois, USA) system, was analysed from 8,315 individuals, aged 40–70 years (average age: 51.3 years). At baseline, several factors, such as medical history, nutritional habits, vital signs, blood tests, electrocardiography, and CGM were monitored, and participants to log their mealtimes. Morning PFG measurements were taken between 6–9 a.m. each day, after a predetermined minimum of 8 hours of fasting.
Results revealed that the average PFG level was 96.2 mg/dl, increasing by 0.234 mg/dl per year of age. Many participants reported significant variability in their PFG levels throughout the study, highlighting the danger of basing diabetes diagnosis on PFG levels. The intraperson day-to-day variability expressed as 7.52±4.31 mg/dl. Most notably, the researchers revealed that among the 5,328 who were initially considered to have normal PFG based their first PFG measurement, 40% and 3% would be later classified as in the prediabetes and diabetes PFG range.
Commenting on these findings, Shilo remarked: ‘Our findings suggest that careful consideration is necessary when interpreting fasting glucose, as substantial intraperson variability exists, and highlights the potential impact of using CGM data to refine glycaemic status assessment.’ The study helps to spotlight the variability in PFG levels, leading to potential misdiagnosis, and thus delayed treatment for asymptomatic diabetics.
