We conducted a prospective study on 330 pregnant women with GDM, followed at the Unit of Endocrinology, University of Palermo (Italy) from January 2018 to December 2020. Inclusion criteria were women with GDM aged more than 18 years. Exclusion criteria were twin pregnancies, women with T1DM on insulin therapy using continuous subcutaneous insulin infusion and women with T2DM, pre-existing renal or cardiac disease, and low diet compliance. The research team included the principal investigator and the sub-investigator and the nurse who performed blood analysis.
The diagnosis of GDM was made according to the International Association of Diabetes and Pregnancy Study Groups and World Health Organization between the 10th and 29th weeks of gestation [16, 17]. It was diagnosed when fasting glucose was ≥ 92 mg/dL before 16th week of gestation or when at least one serum glucose level was more than the expected threshold of 92, 180 and 153 mg/dl for fasting, 1h and 2 h respectively, after an oral glucose tolerance test at 16-18 weeks or 24-28 weeks of gestation [17, 18]. Women were divided into two groups: women supplemented with myoinositol at the dose of 4000 mg/day and women not supplemented with myoinositol (controls). Detailed information were provided about myoinositol beneficial effects in preventing GDM and treating PCOS reporting the results of the published several studies. Controls rejected the treatment due to the lack of largest studies on myoinositol treatment in GDM. The dose of myoinositol was chosen according to the previous studies conducted in prevention of GDM . Myoinositol was started at the diagnosis of GDM and continued until the delivery. This intervention was designed by our diabetologist research team.
During the first visit, a detailed medical history was collected for each patient, including previous obstetric history, recurrent pregnancy loss (RPL), family and personal history of chronic disease. Pregestational anthropometric parameters including weight, height and body mass index were registered. Fasting blood glucose, glycated haemoglobin and urine were assayed. Patients were instructed to follow a specific nutrition plan based on their pregestational BMI and weight. In addition, they were trained in self-monitoring of blood glucose (SMBG) using a glucose meter, with the instruction to perform a minimum of 4 daily measurements (before and 1 hour after meals), as previously reported . The American Diabetes Association and the American College of Obstetricians and Gynecologist (ACOG) recommend similar glucose targets for women with pre-existing diabetes and GDM as follows: fasting glucose less than or equal to 95 mg/dL (5.28 mmol/L), 1 hour after eating less than or equal to 140 mg/dL (7.78 mmol/L) and 2 hours after eating less than or equal to 120 mg/dL (6.67 mmol/L) [11, 21]. For women with uncontrolled glucose values for at least 7 days, insulin therapy was started and the total daily insulin requirement was calculated. The insulin regimen was chosen based on blood glucose values. Basal and short-acting insulins were initiated in women with fasting or postprandial glucose values higher than above-mentioned targets, respectively. The dose was calculated according to the weight about 0.2-0.4 U/kg.
We defined women as underweight when pregestational BMI <18.5 kg/m2, normal weight when BMI was between 18.5 and 24.9 kg/m2, overweight when BMI was between 24.91-29.9 kg/m2 and obese when BMI was more than 29.9 kg/m2. HbA1c was repeated every three months.
The outpatient visits were twice-three times-weekly until delivery. Acute complications were recorded during follow-up: episodes of ketosis, ketoacidosis and maternal hypoglycaemic events. Mean fasting plasma glucose (FPG), postprandial breakfast glucose (PBG), postprandial lunch glucose (PLG) and postprandial dinner glucose (PDG) were recorded for each patient during the visits.
Pre-gestational arterial hypertension was defined with detection of systolic blood pressure values >140 mmHg; diastolic >90 mmHg and/or taking antihypertensive drugs before pregnancy. As maternal outcomes we evaluated pregnancy-induced hypertension defined by detection of systolic blood pressure values >140 mmHg and diastolic >90 mmHg after the 20th week of gestation, preeclampsia defined by the combination of arterial hypertension and proteinuria >300 mg/24h, recurrent ketonuria and glycosuria, evaluated by dip-and-read test strip dipped into a morning urine sample and we defined abnormal an urinary result over 2+, pregnancy loss before the 24th week of gestation, defined as spontaneous abortion, caesarean section and preterm delivery. Preterm birth was defined as completion of gestation before the 37th week.
Perinatal/neonatal outcomes such as birth weight (grams and percentiles), birth length (cm and percentiles), large and small for gestational age were defined as birth weight <10th and ≥90th percentiles, respectively, neonatal hypoglycaemia defined as capillary blood glucose <3.3 mmol/L, hypocalcaemia, hyperbilirubinemia, neonatal intensive care unit admission and respiratory distress syndrome were also assessed.
Data collection involved the following steps: identification of issues and opportunities for collecting data, the creation of a data-collection plan, the actual collection of the data and the analysis and interpretation of data collected. The reliability of instruments used to measure blood parameters was assessed by test-retest reliability by an expert team. Quality data collectors had specifical technical skills including sorting data, creating statistical models, administering surveys, delivering presentations and reports, cleaning data, making corrections, and doing basic statistical work.
All patients provided written informed consent. The study protocol was approved by the Ethics Committee of the Policlinico Paolo Giaccone hospital.
Sample size was calculated based on the mean prevalence of 30% GDM in the worldwide, with a confidence level of 95% and a margin error of 5%.
SPSS version 17 and MedCalc version 11.3 were used for data analysis. Baseline characteristics were presented as mean ± SD for continuous variables; rates and proportions were calculated for categorical data. Normality of distribution for quantitative data was assessed by the Shapiro-Wilk test. The differences between the two groups (myoinositol treated vs. not treated) were detected by the unpaired Student’s t test for continuous variables (after testing for equality of variance: Levene test) and by the χ2 test and Fisher’s exact test (when appropriate) for categorical variables.
The differences between the two groups with p-values less than 0.05 were considered statistically significant.
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