Development and validation of a risk assessment model for prediabetes in China national diabetes survey

Figure 1 Flowchart for trimmed data in the China National Diabetes and Metabolic Disorders Study derivation dataset, data cleaning in the National Health and Nutrition Examination Survey validation dataset and data arrangement in the Thyroid Disorders, Iodine Status and Diabetes Epidemiological Survey study. A: In the China National Diabetes and Metabolic Disorders Study (CNDMDS) study, 47325 completed the survey. After excluding 6035 participants diagnosed with diabetes and 887 with missing information on key variables, there were 40403 nondiabetic participants available for our analysis. After excluding those with outlier influences of waist circumference, body mass index, systolic blood pressure and diastolic blood pressure, 40381 participants were ultimately included in the derivation dataset for model development and internal validation; B: In National Health and Nutrition Examination Survey, data from 9364 participants were available. After excluding 894 participants diagnosed with diabetes and 6359 with missing fasting glucose level or oral glucose tolerance test data, there were 2111 nondiabetic participants available for our analysis. After excluding the 586 participants with missing key variables, 1525 nondiabetic individuals were available for external validation; C: In the TIDE study, 80937 subjects participated in the survey. A total of 5057 subjects were excluded due to a lack of information on age, sex, glucose levels or HbA1c. A total of 9772 participants diagnosed with diabetes were further excluded, leaving 66108 participants in the analysis. CNDMDS: China National Diabetes and Metabolic Disorders Study; DBP: Diastolic blood pressure; OGTT: Oral glucose tolerance test; NHANES: National Health and Nutrition Examination Survey; TIDE: Thyroid disorders, Iodine status and Diabetes Epidemiological survey.