Method (s) Tianjin three-tier antenatal care network established a universal screening program for gestational diabetes mellitus (GDM) in 1998 and up to 2008, the screening program had screened 115348 pregnant women. GDM will be defined as either fasting plasma glucose (PG) ≥5.1 mmol/L or 1-hour PG≥ 10.0 mmol/L or 2-hour PG≥ 8.5 mmol/L after 75 g glucose tolerance test. A total of 920 pregnant women who have GDM and agree to participate will be randomly assign to have the shared care (diet, physical activity and insulin if indicated) or the local usual antenatal care. The sample size has ≥80% power at a 5% type I error to detect the difference in the primary endpoint, birth weight ≥4000 gram and the secondary endpoint, pregnancy-induced hypertension. Hyperglycemia and other clinical data in the two groups of women will be collected during the shared care or the usual care. Logistic regression and cost-effectiveness analysis will be used in the data analysis.