Non-diabetes status after diagnosis of impaired glucose tolerance and risk of long-term death and vascular complications: A post hoc analysis of the Da Qing Diabetes Prevention Outcome Study.

Background: The association between years of non-diabetes status after diagnosis of impaired glucose tolerance (IGT) and the risk of long-term death and cardiovascular outcomes needed to be clarified. Methods and findings: In this post hoc analysis, we included 540 individuals with IGT who participated in the original Da Qing Diabetes Prevention Study (DQDPS). In the DQDPS, all participants were diagnosed with IGT by a 75 g oral glucose tolerance test and randomized to intervention or control groups with a 6-year lifestyle intervention trial. After the completion of the trial, death, cardiovascular events, and microvascular complications were monitored over a 30-year follow-up. In this post hoc analysis, the Cox analysis assessed the extended risk of these outcomes in individuals who either remained non-diabetes status or progressed to diabetes at the end of 2, 4, and 6 years after diagnosis of IGT. In all participants, the difference in the cumulative incidence rate of the outcomes between the diabetes and non-diabetes group gradually increased over 30 years. Compared with the diabetes group, a significantly lower risk of all-cause death (hazard ratio [HR]: 0.74; 95% confidence interval [CI]: 0.57 to 0.97, p = 0.026), cardiovascular events (HR: 0.63; 95% CI: 0.49 to 0.82, p < 0.001), and microvascular complications (HR: 0.62; 95% CI: 0.45 to 0.86, p = 0.004) first emerged in individuals who remained non-diabetes at the 4 years visit, whereas the significant risk reduction in cardiovascular death was first observed at the end of 6 years (HR: 0.56; 95% CI: 0.39 to 0.81, p = 0.002) after adjustment for age, sex, smoking status, BMI, systolic blood pressure, blood glucose, total cholesterol, intervention, and medications (including insulin plus oral hypoglycaemics, antihypertensives, and lipid-lowering agents). The results in the original intervention group alone were similar to the whole group. The main limitations of our study are the limited number of participants and the sole ethnicity of the Chinese population. Conclusions: In this study, we observed that maintaining several years of non-diabetes status after IGT diagnosis was associated with a significant reduction in long-term risk of death and vascular complications, and for most of these outcomes, maintaining at least 4 years of non-diabetes status may be needed to achieve a significant risk reduction. Xin Qian and co-authors explore how the duration of a lifestyle intervention for diabetes prevention influences length of time spent in non-diabetes status after a diagnosis of impaired glucose tolerance and, the impact on long term outcomes. Author summary: Why was this study done?: Lifestyle intervention can reduce or delay the incidence of diabetes in people with impaired glucose tolerance (IGT). Major lifestyle intervention trials have shown that lifestyle intervention can improve microvascular complications and some cardiovascular risk factors. To the best of our knowledge, no study has reported the relationship between long-term outcomes and duration of maintaining non-diabetes status after a diagnosis of IGT which may be influenced by the duration of lifestyle intervention, after IGT diagnosis. What did the researchers do and find?: We conducted a post hoc analysis of the China Da Qing Diabetes Prevention Study (DQDPS), a 6-year lifestyle intervention trial in people with IGT. In this study, we included 540 individuals with IGT and assessed the long-term risk of mortality, macro- and microvascular diseases between those who remained non-diabetes status or not at the end of 2, 4, and 6 years visit after diagnosis of IGT. Our analyses showed that individuals who remained non-diabetic for at least 4 years after being diagnosed with IGT had a significantly lower risk of all-cause death, cardiovascular events, and microvascular complications compared with those who progressed to diabetes. However, this effect was not observed in individuals who remained non-diabetic for a shorter period. What do these findings mean?: This post hoc analysis suggests that a longer duration of non-diabetes status in those with IGT has beneficial health outcomes and reduces mortality. The implementation of effective interventions targeting those with IGT should be considered as part of preventative management for diabetes and diabetes-related vascular complications. The main limitations of this study are the limited number of participants and the sole ethnicity of the Chinese population. [ABSTRACT FROM AUTHOR]