Objective       To access the clinical differences and results of outcomes continuous glucose monitor system (CGM

S) in newly diagnosed overt diabetes mellitus and gestational diabetes mellitus.       Methods       Patients who were newly diagnosed as diabetes mellitus during mid trimester of pregnancy from Department of Endocrinology and Metabolism of our hospital during June 2010 to June 2012 were collected in this study. According to IADPSG standards

they were diagnosed as overt diabetes mellitus (ODM group

n=27) and as gestational diabetes mellitus (GDM group

n=35). The CGMS results and other clinical data were comparatively analyzed in the 2 groups.       Results       Compared with the GDM group

the prevalence of diabetes family history (40.74% 

vs 

17.10%

P

0.05)

the total time of hyperglycemia (1361.70±627.50

vs

470.00±320.00 min

P

0.05)

the incidence of hyperglycemia (7.89±4.49 vs 5.54±3.30

P

0.05)

and mean amplitude of glycemic excursions (MAGE)(4.35±1.5 

vs 

3.29±1.27 mmol/L

P

0.05）were significantly higher in the ODM group. The 2-hour postprandial hyperglycemia was lower (10.12±1.76

vs

13.08±3.68 mmol/L

P

0.05)

but the total time of hypoglycemia (167.60 ±175.20

vs

56.80±83.20 min

P

0.05)

incidences of hypoglycemia (2.83±3.49

vs

0.74±0.90

P

0.05)

and number of nocturnal hypoglycemia (1.94±2.79

vs

0.48±0.70

P

0.05) were significantly higher in GDM group than ODM group (

P

0.05).       Conclusion       ODM patients have higher prevalence of diabetes family history

and hyperglycemia and higher glucose variability as main occurrences

while GDM patients have mild postprandial hyperglycemia

and preprandial hypoglycemia or nocturnal hypoglycemia as main manifestations.