The relative risk of developing type 2 diabetes among individuals with prediabetes compared with individuals with normoglycaemia: Meta-analysis and meta-regression.

Aims: To assess the overall relative risk of diabetes in individuals with prediabetes based on updated diagnostic criteria, as compared with individuals with normoglycaemia; and to identify the study characteristics associated with the heterogeneity between studies.

Design: Meta-analysis, meta-regression.

Data Sources: PubMed, CINAHL, British Nursing Index. Search time frame: December 1998-December 2018.

Review Methods: The pooled relative risk of developing diabetes among individuals with prediabetes compared with those with normoglycaemia was calculated under a random effects model. Studies reported the natural progression from prediabetes to diabetes were included in this review. Sources of study heterogeneity were examined by a meta-regression.

Results: Fifty-nine eligible studies were systematically identified. The pooled relative risk for diabetes among individuals with prediabetes as compared with normoglycaemia was 5.88 (95% CI: 5.02-6.89). The annualized incidence rate (per 1,000 person-year) for diabetes among individuals with prediabetes defined by different criteria varied from 2.20-212.15, with high heterogeneity between studies (I  = 96.64%, Q test: p < .001). In the multivariable meta-regression analysis, Asian population significantly increased RR compare to Caucasians. Besides, people with 'elevated glycated haemoglobin A1c or impaired fasting glucose' had highest relative risk compare to people with other types of prediabetes.

Conclusion: Individuals with prediabetes had higher risk of developing diabetes than those with normoglycaemia. Races and diagnostic criteria of prediabetes were associated with the magnitude of the estimated risk.

Impact: Prediabetes is a precursor of diabetes. To screen people with prediabetes as early as possible, practitioners could consider haemoglobin A1c test as an alternative to fasting plasma glucose test. Nurses should educate people especially Asians with prediabetes for the prevention of progression to diabetes.