We investigated the association between changes in weight status from childhood through adulthood and subsequent type 2 diabetes risks and whether educational attainment, smoking, and leisure time physical activity (LTPA) modify this association.Using data from 10 Danish and Finnish cohorts including 25,283 individuals, childhood BMI at 7 and 12 years was categorized as normal or high using age- and sex-specific cutoffs (<85th or 85th percentile). Adult BMI (20-71 years) was categorized as nonobese or obese (<30.0 or 30.0 kg/m2, respectively). Associations between BMI patterns and type 2 diabetes (989 women and 1,370 men) were analyzed using Cox proportional hazard regressions and meta-analysis techniques.Compared with individuals with a normal BMI at 7 years and without adult obesity, those with a high BMI at 7 years and adult obesity had higher type 2 diabetes risks (hazard ratio [HR]girls: 5.04 [95% CI 3.92-6.48]; HRboys: 3.78 [95% CI 2.68-5.33]). Individuals with a high BMI at 7 years but without adult obesity did not have a higher risk (HRgirls: 0.74 [95% CI 0.52-1.06]; HRboys: 0.93 [95% CI 0.65-1.33]). Education, smoking, and LTPA were associated with diabetes risks, but did not modify or confound the associations with BMI changes. Results for 12 years of age were similar.A high BMI in childhood was associated with higher type 2 diabetes risks only if individuals also had obesity in adulthood. These associations were not influenced by educational and lifestyle factors, indicating that BMI is similarly related to the risk across all levels of these factors.