Abstract and Introduction
Abstract
Background: Lifestyle intervention decreases diabetes risk in prediabetic subjects, but the impact of passive notification of prediabetes status on glycemia or health behavior is unclear.
Methods: The Pathobiology of Prediabetes in a Biracial Cohort (POP-ABC) study followed normoglycemic African American (AA) and European American (EA) offspring of parents with type 2 diabetes mellitus for incident prediabetes. During 5.5 years of follow-up (mean, 2.62 years), 101 of 343 subjects developed prediabetes and were notified, without any interventions. Participants were recalled 18 months poststudy. Here, we compared data from participants with incident prediabetes or normoglycemia (control) during POP-ABC who underwent retesting 18-months poststudy.
Results: There were 73 subjects (46 female, 27 male; 36 AA, 37 EA) in the prediabetes group and 73 subjects (48 female, 25 male; 35 AA, 38 EA) in the control group. The mean (± SEM) enrollment age was 48.7 ± 0.96 years versus 48.3 ± 1.06 years (P = .37) and body mass index (BMI) was 31.1 ± 0.70 kg/m2 versus 29.2 ± 0.69 kg/m2 (P = .04) for prediabetes versus control groups, respectively. The 18-month changes (prediabetes vs control) were the following: fasting plasma glucose (FPG), −8.01 ± 1.11 vs 2.02 ± 0.64 mg/dL; 2-hour plasma glucose (2hrPG), −8.21 ± 3.34 vs 8.53 ± 3.17 mg/dL; weight, −0.54 ± 0.72 vs 2.77 ± 1.25 kg; and waist circumference −1.07 ± 0.78 vs 1.78 ± 0.85 (P = .03-<0.0001). The interval changes in FPG were significantly correlated with changes in weight and waist circumference (r = 0.2, P = .01). The prediabetes group reported improved dietary and exercise habits compared with control.
Conclusion: Communication of prediabetes status is associated with improvements in glucose tolerance, glycemia, and adiposity, probably via self-directed lifestyle modification.
Introduction
The Department of Health and Human Services (HHS) and the American Diabetes Association (ADA) drew attention to prediabetes at a joint press conference: "HHS and the ADA are using the new term 'prediabetes' to describe an increasingly common condition in which blood glucose levels are higher than normal but not yet diabetic—known in medicine as impaired glucose tolerance (IGT) or impaired fasting glucose (IFG). Studies have shown that most people with this condition go on to develop type 2 diabetes within 10 years."[1] The Centers for Disease Control and Prevention estimates that 84.1 million US adults aged 18 years or older (~34% of the adult US population) had prediabetes in 2015.[2] Worldwide, more than 300 million people are estimated to have prediabetes.[3]
The diagnosis of prediabetes is established by the documentation of IFG, indicated by a fasting plasma glucose (FPG) level of 100 mg/dL to 125 mg/dL (5.6–6.9 mmol/L) or IGT, indicated by a 2-hour plasma glucose (2hrPG) level of 140 mg/dL to 199 mg/dL (7.8–11.0 mmol/L) during a 75-g oral glucose tolerance test (OGTT).[4,5] Hemoglobin A1c (HbA1c) levels of 5.7–6.4% are also diagnostic of prediabetes.[4] Besides the risk of developing type 2 diabetes mellitus (T2DM), people with prediabetes are at increased risks for heart disease, stroke, neuropathy, and other microvascular complications.[6–8]
Several landmark clinical trials have demonstrated that lifestyle modification decreases blood glucose levels and prevents progression to T2DM in persons with prevalent prediabetes.[9,12] In those studies, teams of dietitians, exercise physiologists, and other clinicians executed the standard lifestyle intervention protocols that led to the improvement in glucose tolerance and successful prevention of T2DM in study participants.[9,11,13] Compared with the placebo group, individuals assigned to lifestyle intervention experienced 40–58% relative reduction in the risk of developing T2DM.[9,11] Notably, the participants in the landmark diabetes prevention studies all had prevalent prediabetes determined during cross-sectional population screening and, therefore, of unknown duration at enrollment.[9–11]
The impact of awareness of incident prediabetes status on glycemic trajectories among previously normoglycemic persons is unknown, and cross-sectional surveys show conflicting reports regarding the impact of such awareness on self-directed health behavior.[14,15] The Pathobiology of Prediabetes in A Biracial Cohort (POP-ABC)[16,17] study enrolled normoglycemic African American (AA) and European American (EA) offspring of parents with T2DM and followed them for the occurrence of incident prediabetes, defined as IFG and/or IGT.[4,5] All POP-ABC study participants completed a screening OGTT before enrollment. The first subject was enrolled in September 2006, and the POP-ABC study ended in February 2012 after the final follow-up visits. During ~5 years of follow-up, 101 of 343 subjects developed prediabetes and were duly notified, without any active intervention or counseling, as POP-ABC was a natural history study.
Eighteen months after the study ended, POP-ABC study participants were invited to return for OGTT and clinical examination, as part of the screening procedures for a newly funded Pathobiology and Reversibility of Prediabetes in A Biracial Cohort (PROP-ABC) study, whose aims include intensive lifestyle intervention to reverse prediabetes (ClinicalTrials.gov Identifier NCT02027571). Here, we report temporal changes in glucose and other metabolic measures between the end of POP-ABC and the beginning of PROP-ABC (18 months later) in participants with incident prediabetes during POP-ABC (pre-diabetes mellitus group) compared with a matched group of POP-ABC participants who did not develop prediabetes.
J Am Board Fam Med. 2019;32(1):20-27. © 2019 American Board of Family Medicine