FGF23 and diabetes mellitus: The results of subgroup analyses showed higher heterogeneity in longitudinal studies regarding age, greater heterogeneity in cross-sectional and longitudinal studies for dialysis treatment duration and FGF-23, and greater heterogeneity in cross-sectional and case–control studies for diabetes when analyzed from the perspective of study type; however, subgroup analyses of case–control studies regarding dialysis treatment duration did not yield a statistically significant effect.