Conclusions HbA1c is neither sensitive nor specific for detecting pre‐diabetes ; fasting glucose is specific but not sensitive .
Interventions in people classified through screening as having pre‐diabetes have some efficacy in preventing or delaying onset of type 2 diabetes in trial population s. As screening is inaccurate , many people will receives an incorrect diagnosis and be referred on for interventions while others will be falsely reassured and not offered the intervention .
These findings suggest that “ screen and treat ” policies alone are unlikely to have substantial impact on the worsening epidemic of type 2 diabetes .
& NA ; Objectives To assess diagnostic accuracy of screening tests for  pre‐diabetes  and efficacy of interventions ( lifestyle or metformin ) in preventing onset of type 2 diabetes in people with pre‐diabetes .
Lifestyle modification and prevention of type 2 diabetes in overweight Japanese with impaired fasting glucose levels: a randomized controlled trial.
BACKGROUND Previous studies demonstrated that intensive lifestyle modification can prevent type 2 diabetes mellitus among those with impaired glucose tolerance , but similar beneficial results have not been proved among those with impaired fasting glucose levels . We investigated the efficacy of lifestyle modification on  type 2 diabetes  incidence among those with impaired fasting glucose levels . METHODS The present study was an unmasked , multicenter , r and omized , controlled trial . A total of 641 overweight Japanese ( aged 30 - 60 years ) with impaired fasting glucose levels were recruited nationwide in Japan and r and omly assigned to a frequent intervention group ( n = 311 ) or a control group ( n = 330 ) . For 36 months after r and omization , the frequent intervention group received individual instructions and follow-up support for lifestyle modification from the medical staff 9 times . The control group received similar individual instructions 4 times at 12-month intervals during the same period . The primary outcome was type 2 diabetes incidence in annual 75-g oral glucose tolerance tests , diagnosed according to World Health Organization criteria . RESULTS There were no significant differences between the allocation groups in baseline characteristics and dropout rates . Estimated cumulative incidences of type 2 diabetes were 12.2 % in the frequent intervention group and 16.6 % in the control group . Overall , the adjusted hazard ratio in the frequent intervention group was 0.56 ( 95 % confidence interval , 0.36 - 0.87 ) . In the post hoc subgroup analyses , the hazard ratio reduced to 0.41 ( 95 % confidence interval , 0.24 - 0.69 ) among participants with impaired glucose tolerance at baseline , and to 0.24 ( 0.12 - 0.48 ) among those with baseline hemoglobin A(1c ) levels of 5.6 % or more ( the Japan Diabetes Society method ) . Such risk reduction was not observed among those with isolated impaired fasting glucose findings or baseline hemoglobin A(1c ) levels of less than 5.6 % . CONCLUSIONS Lifestyle modifications can prevent type 2 diabetes  among overweight Japanese with impaired fasting glucose levels . In addition , identifying individuals with more deteriorated glycemic status by using 75-g oral glucose tolerance test findings or , especially , measurement of hemoglobin A(1c ) levels , could enhance the efficacy of lifestyle modifications . TRIAL REGISTRATION umin.ac.jp/ctr Identifier : UMIN000001959
Conclusions HbA1c is neither sensitive nor specific for detecting pre‐diabetes ; fasting glucose is specific but not sensitive .
Interventions in people classified through screening as having pre‐diabetes have some efficacy in preventing or delaying onset of type 2 diabetes in trial population s. As screening is inaccurate , many people will receives an incorrect diagnosis and be referred on for interventions while others will be falsely reassured and not offered the intervention .
These findings suggest that “ screen and treat ” policies alone are unlikely to have substantial impact on the worsening epidemic of type 2 diabetes .
& NA ; Objectives To assess diagnostic accuracy of screening tests for  pre‐diabetes  and efficacy of interventions ( lifestyle or metformin ) in preventing onset of type 2 diabetes in people with pre‐diabetes .