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 .
The long-term effect of lifestyle interventions to prevent diabetes in the China Da Qing Diabetes Prevention Study: a 20-year follow-up study
BACKGROUND Intensive lifestyle interventions can reduce the incidence of  type 2 diabetes in people with impaired glucose tolerance , but how long these benefits extend beyond the period of active intervention , and whether such interventions reduce the risk of cardiovascular disease ( CVD ) and mortality , is unclear . We aim ed to assess whether intensive lifestyle interventions have a long-term effect on the risk of diabetes , diabetes-related macrovascular and microvascular complications , and mortality . METHODS In 1986 , 577 adults with impaired glucose tolerance from 33 clinics in China were r and omly assigned to either the  control group or to one of three lifestyle intervention groups ( diet , exercise , or diet plus exercise ) . Active intervention took place over 6 years until 1992 . In 2006 , study participants were followed-up to assess the long-term effect of the interventions . The primary outcomes were diabetes incidence , CVD incidence and mortality , and all-cause mortality . FINDINGS Compared with control participants , those in the combined lifestyle intervention groups had a 51 % lower incidence of diabetes ( hazard rate ratio [ HRR ] 0.49 ; 95 % CI 0.33 - 0.73 ) during the active intervention period and a 43 % lower incidence ( 0.57 ; 0.41 - 0.81 ) over the 20 year period , controlled for age and clustering by clinic . The average annual incidence of diabetes was 7 % for intervention participants versus 11 % in control participants , with 20-year cumulative incidence of 80 % in the intervention groups and 93 % in the control group . Participants in the intervention group spent an average of 3.6 fewer years with diabetes than those in the control group . There was no significant difference between the intervention and control groups in the rate of first CVD events ( HRR 0.98 ; 95 % CI 0.71 - 1.37 ) , CVD mortality ( 0.83 ; 0.48 - 1.40 ) , and all-cause mortality ( 0.96 ; 0.65 - 1.41 ) , but our study had limited statistical power to detect differences for these outcomes . INTERPRETATION Group-based lifestyle interventions over 6 years can prevent or delay diabetes for up to 14 years after the active intervention . However , whether lifestyle intervention also leads to reduced CVD and mortality remains unclear
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 .