Diabetes Prevention: Efficacy of Screen-and-Treat Policies

Screen-and-treat policies alone are unlikely to have a substantial effect on the prevention of type 2 diabetes, according to a study published inThe BMJ.

For the study, investigators sought to identify all diagnostic and accuracy and prevalence studies that focus on laboratory assessed hemoglobin A1C (HbA1C) and fasting plasma glucose as screening tools. However, capillary glucose and HbA1C point-of-care testing were excluded.

The 2 types of interventions studied were lifestyle programs and metformin, compared with a control, in any setting, and that included weight change, change in glycemic index, or diabetes incidence as an outcome.

The intervention studies included had participants 18 years and older who had been identified as being in one of the at-risk groups: impaired glucose tolerance, impaired fasting glucose, raised HbA1C, or a history of gestational diabetes, according to the study.

The investigators conducted 2 meta-analyses: the first summarized the accuracy of screening tests—–with the oral glucose tolerance test as the standard––for identifying prediabetes. The other analysis assessed the relative risk of progression to type 2 diabetes after either lifestyle intervention or treatment with metformin.

In total, 148 publications were fully reviewed, with 83 regarding diagnostic testing and 65 relating to intervention trials. Data were extracted from 46 papers and used to construct the diagnostic accuracy meta-analysis. Additionally, the investigators reviewed 50 unique intervention trials in full and related publications.

The final analysis included 49 studies of screening tests, 5 of which were prevalence studies and 50 were intervention trials.

The results of the study showed that HbA1C had a mean sensitivity of 0.49 (95% CI, 0.40 to 0.58), and a specificity of 0.79 (0.73 to 0.84) for identification of prediabetes. Fasting plasma glucose had a mean sensitivity of 0.25 (0.19 to 0.32) and specificity of 0.94 (0.92 to 0.96). The authors noted that different measures of glycemic abnormality identified different subpopulations.

For lifestyle interventions, the results of the study showed an association with a 36% (28% to 43%) reduction in relative risk of type 2 diabetes over 6 months to 6 years, reducing to 20% (8% to 31%) at follow-up post-trials.

The study authors concluded that HbA1Cwas neither sensitive nor specific for identifying pre-diabetes, and that fasting glucose is specific but is not sensitive. The interventions in individuals who were classified as having prediabetes through screening, do have some efficacy in the prevention or delayed onset of type 2 diabetes in trial populations.

Unfortunately, inaccurate screenings can provide individuals with an incorrect diagnosis and be referred on for interventions. Others can be falsely reassured instead of being offered the intervention, according to the study.

The study findings suggest that screen-and-treat policies alone are unlikely to have a substantial impact on the type 2 diabetes epidemic, according to the authors.