Diagnosis and Management of Prediabetes: A Review

Prediabetes isa highly prevalent intermediate stage of glucose dysregulation that may precede type 2 diabetes. In the United States, approximately 10% of those with prediabetes will develop diabetes each year, and the prevalence of prediabetes is steadily increasing. The aim of this review is to summarize the epidemiology, diagnostic criteria, clinical outcomes, and management of pre -diabetes. A literature search was conducted for high-quality prospective cohort studies, randomized trials, systematic reviews, and meta-analyses. For the purpose of this review, outcomes associated with cases defined by fasting plasma glucose level, 2-hour plasma glucose level after a 75-g oral glucose challenge (2hPG), or glycosylated hemoglobin (HbA1c) level were in-cluded. Different diagnostic criteria for prediabetes are reported by the American Diabetes Association, the World Health Organization, and the International Expert Committee; however, a fasting plasma glucose of greater than 100, a 2hPG of greater than 140, or an HbA1c of greater than 6.0 would qualify by each organization's standards. Nationally representative surveys were queried to obtain estimates of disease frequency. A total of 110 studies were included, including 20 randomized clinical trials, 9 systematic reviews and meta-analyses, 7 guide-lines, 3 diagnostic studies, 58 cohort studies, and results of 13 nationally representative surveys. Longitudinal studies revealed an incident prediabetes rate of 6.2% among predominantly White participants, 7.8% among people those identifying as Pima In-dian, and 11% among Black or White adults with parental history of type 2 diabetes. Risk factors for the development of pre -diabetes include overweight or obesity, older age, physical inactivity, unhealthy diet, and genetic predisposition. A meta-analysis revealed that a history of diabetes in at least 1 first-degree relative was associated with increased odds of having prediabetes (odds ratio, 1.40; 95% confidence interval, 1.27-1.54). One observational study found that 102 of 265 participants with predi-abetes progressed to diabetes during 10 years of follow-up, whereas another found the cumulative diabetes incidence was 95.9% among participants with prediabetes without treatment over a 30-year follow-up period. Another study found that of the 3 diag-nostic methods the highest relative risk for development of diabetes from prediabetes was associated with a high HbA1c.A meta-analysis of 129 prospective studies found that prediabetes was associated with increased rates of cardiovascular disease (incidence rate per 10,000 person-years, 58.3 in those with normal glucose regulation vs 67.0 among those with pre -diabetes) and all-cause mortality (73.6 among those with normal glucose regulation and 81 among those with prediabetes). In addition, microvascular complications including retinopathy, peripheral neuropathy, and chronic kidney disease are frequent among those with prediabetes. Lifestyle modifications such as increased exercise anda healthy diet are the mainstays of treat-ment for prediabetes. Interventions targeting these pillars have shown a decrease in the incidence of diabetes compared with placebo or usual care among those with prediabetes and women with a history of gestational diabetes. In addition, several randomized clinical trials have shown metformin may reduce the incidence of diabetes among people with prediabetes; however, it was less efficacious than lifestyle intervention. The results of this review show that prediabetes is associated with increased risk of diabetes, cardiovascular events, and mortality and should be treated with lifestyle modification that includes weight loss and exercise with or without metformin.