Scanning frequency and glucose variability in the first trimester of T1DM pregnancies predict time spent in very low glucose range in the last one: analysis of intermittently scanned continuous glucose monitoring
Hypoglycemia is inevitable side effect of tight glycemic control in type 1 diabetes mellitus (T1DM) pregnancies. Using technology novel risk factors are revealed. Total of 34 patients (mean age 29.8 ± 6.1 yrs, BMI 23.6± 3.6 kg/m2, disease duration 15.2± 8.9 yrs) having very low glycemia in third trimester (< 3 mmol/L or 55 mg/dL) were included in the study. Patients used intermittently scanned continuous glucose monitoring (isCGM) FreeStyle Libre, Abott for a minimum of 3 months before conception and had glucose data availability > 80% of the time. Data from first trimester showed mean scanning frequency 12.17 ± 6.5 scans/day, estimated average glucose 7.2 ± 1.4 mmol/L, CV% 41.9 ± 6.5, GMI 6.4 ± 0.5, time below range <3.5 mmol/L or 64 mg/dL 10.7 ± 8.0 % and time spent in very low glucose range <3mmol/L or 55 mg/dL 5.4 ± 4.9 %. In last trimester mean scanning frequency was 16.3 ± 7.6 scans/day, estimated average glucose 6.1 ± 0.9 mmol/L, CV% 34.6 ±6.0 , GMI 5.9 ± 0.4 , time below range 11.0 ±9.3 %, time spent in very low glucose range 5.2 ± 4.8 %. Parameters from the first trimester of pregnancy significantly correlating with time spent in very low glucose range in the third trimester were scanning frequency (r −0.365, p 0.37) and CV % (r 0.465, p 0.006) . Linear regression analysis performed for CV% and scanning frequency showed R square 0.434 and p 0.002 in ANOVA. Two isCGM parameters from first trimester of pregnancy that influence on very low glucose rate in the third one are low scanning frequency and higher %CV. Combined they add to 43% of very low glucose occurrence. Patients who scan frequently in the first trimester of pregnancy and have low glucose variability spend less time in very low glucose range in the third trimester. For the others continuous glucose monitoring with hypo alerts should be offered.
M. Baretic: None. G. Leksic: None. M. Ivanisevic: None.