Characteristics and clinical significance of daily blood glucose profiles in patients with gestational diabetes mellitus monitored by continuous glucose monitoring system

Objective To investigate the characteristics of the daily blood glucose profiles in patients with gestational diabetes mellitus(GDM) by continuous glucose monitoring system(CGMS) so as to guide the clinical treatment. Methods The glucose level in the subcutaneous tissue was monitored by CGMS for 3 days in 7 patients with GDM and 20 participants with normal glucose tolerance(NGT). The average age was 28 and 41 yrs in GDM and NGT group, respectively. The average body mass index(BMI) was 25 and 24 kg/m2 in GDM and NGT group, respectively. After 3-day CGMS, the GDM patients were administrated with multiple daily insulin injections. The mean plasma glucose(MPG), standard deviation of blood glucose (SDBG), mean amplitude of glucose excursions(MAGE), postprandial glucose excursions(PPGE), mean of daily differences (MODD) and difference between maximal and minimal glucose (DMMG) were calculated with the data obtained from CGMS. The insulin dose was recorded when glucose level achieved the target. The t test was used to compare the difference between groups and the difference of postprandial glucose excursions in GDM group. Results The MAGE, PPGE and DMMG were significantly higher in GDM group (MAGE (4.3±0.2) vs (1.6±0.3) mmol/L; the breakfast postprandial glucose excursions (BPPGE) (5.5±1.1) vs (1.8±0.4) mmol/L; lunch PPGE(LPPGE) (3.1±0.3) vs (1.3±0.2) mmol/L; dinner PPGE(DPPGE) (3.4±0.4) vs (1.5±0.2) mmol/L and DMMG (6.0±2.7) vs (2.9±0.2) mmol/L; t=4.4, 5.6, 2.3, 2.8, 6.1, all P<0.05). There was no significant difference in MBG, SDBG and MODD between GDM and NGT group. Postprandial glucose excursion was higher at breakfast than those at lunch and dinner in GDM group(t=3.1, 2.6, both P<0.05). The basal insulin requirement accounted for 15% of the total daily insulin usage. Pre-breakfast insulin dosage was higher than pre-lunch and pre-dinner doses. The pre-breakfast insulin dosage accounted for 33.5% of total daily insulin usage. Conclusions CGMS is an effective method to assess glycemic excursions in patients with GDM. GDM is characterized by hyper-postprandial glucose and postprandial glucose excursion. Preprandial insulin dose accounts for a majority proportion of total daily dose, within which the pre-breakfast dose is the highest. Insulin dose is consistent with the glucose excursion in GDM patients. Key words: Diabetes, gestational; Insulin; Continuous glucose monitoring system