The prevention and management of GDM can be done by increasing the food consumption rich in antioxidant, fruit and vegetables and also other antioxidant rich sources. 7 Tender coconut water is a natural, healthy, nutritious, provided by nature, easily obtained in tropical countries. Tender coconut ABSTRACT Background: Diabetes during pregnancy or Gestational Diabetes Mellitus (GDM) causes oxidative stress and have bad effect for mother and baby, risk of abortion, still birth, premature and preeclampsia. GDM can be prevented by monitoring the glucose level and providing rich antioxidants meals. TCW is a nutritious healthy drink rich in antioxidants, diet rich in antioxidants promotes better health, Inhibits lipid peroxidation and enhances the total antioxidant status. Aim and Objectives: This research to investigate the effect of tender coconut water can prevent lipid peroxidation, reduce glucose levels and increase insulin plasma level on pregnant diabetic rats. Material and Methods: Experimental study by post test only control group design, population of pregnant wistar strain rats. Twenty four samples used in this study were randomly divided into 4 groups, K1 (pregnant rats), K2 (pregnant rats+diabetic), K3 (pregnant rats+diabetic+ glibenklamid 0.23 mg/kg BW) and K4 (pregnant rats+diabetic+TCW 8mL/200grBW). Diabetes Mellitus were induced using Streptozotocin (STZ) 65mg/kgBW and Nicotinamid 230 mg/kgBW. Data on insulin plasma, glucose and MDA levels were analyzed using One Way Anova with significant level 0.05. Result: The results showed that the average insulin plasma levels in group 2 decreased compared to group 1 , in group 3 and 4 it increased compared to group 2. Average glucose and MDA levels in group 2 increased compared to group 1 , in group 3 and 4 it decreased compared to group 2. The results of the analysis has the p values 0.000 (p<0.05). Conclusion:TCW can inhibit the process of lipid peroxidation, reduce glucose levels, increase insulin plasma levels and in pregnant diabetic rats.