CRP and diabetes mellitus: HbA1c=glycated hemoglobin; FPG=fasting plasma glucose; PD=probing depth; CAL=clinical attachment level; BOP=bleeding on probing; NSPT=non-surgical periodontal therapy; T2DM=type 2 diabetes mellitus; RCT=randomized controlled trial; MD=mean difference; CI=confidence interval; SD=standard deviation; SMD=standardized mean difference; CRP=C-reactive protein; QoL=quality of life.