It is common knowledge that pregnancy is a difficult time in which to achieve good glucose control because of placental hormones, growth factors, and cytokine production together with an increase in insulin resistance [9]. Even women with good dietary knowledge often find glucose control harder to achieve, especially during the early stages of pregnancy when they might be suffering from morning sickness, nausea, or vomiting. Studies have shown that daily insulin requirements may decrease during the first three months of pregnancy as the fetus uses the mother’s body glucose [10]. Hypoglycemia frequently occurs at this stage and up to 70% of women with T1D report such episodes during pregnancy [11]. The high rate of macrosomic babies notwithstanding tight glycemic control has also been attributed to frequent rebound hyperglycemic episodes following hypoglycemia as well as to the hyperglycemia itself [12]. It is therefore advisable for diabetologists to closely follow their patients during pregnancy [13], adequately informing them about the possibility of rapid fluctuations in insulin requirements [14]. To prevent hyper- or hypoglycemia, dietary and lifestyle counseling is crucial, although insulin regimen titration is often the mainstay of treatment. We herein show that even though over half of the women with T1D had been on an individualized diet since before pregnancy, had received adequate counseling on the importance of controlling rapid weight gain to avoid hyperglycaemia and macrosomic babies, and had followed a reported reasonably good dietary regime throughout pregnancy, insulin up-titration was required to maintain good glucose control so as to prevent significant weight gain. Moreover, newborns of women with T1D still had significantly higher body weight compared to controls. This could be due to weight gain or rebound hyperglycemia or is possibly attributable to the increased insulin dosage per se [15]. On the other hand, weight gain could occur for other reasons apart from insulin effects on adipose tissue, including prepregancy lifestyle, smoking habits, alcohol consumption, and sleep time, and this could be a confounder. In this study, none of these aspects appears to be related to weight.

Several other factors have been proposed as being associated with higher gestational weight gain, such as unfavorable obstetric history, prepregnancy overweight/obesity, gestational age at delivery, and length of follow-up [16]. On the other hand, appetite during pregnancy is increased and feedback responses to metabolic hormones, including both leptin and insulin, are suppressed to promote a positive energy balance [17]. Furthermore, hyperemesis, which frequently occurs in pregnant women [18], induces increased consumption of carbohydrates.

All things considered, it seems reasonable to recommend tailored and careful management of pregnant women with normal weight and T1D in order to keep insulin up-titration to a bare minimum. However, a weak correlation was found between daily insulin regimen and weight gain. This should be pursued by further improving nd diet and regular physical activity, with body weight gain being taken into consideration together with glucose control per se, although further, larger studies are warranted to deepen our understanding of the underlying mechanisms regarding this aspect.

In our cohort, women with T1D exhibited a 0.7% mean decrease in HbA1c throughout pregnancy. It is noteworthy that women without diabetes show a reduction in HbA1c levels during the first trimester as a decrease in red blood cell life span. Similarly, women with T1D seem to experience a slight reduction independent of glucose control due to the same mechanism [19]. Our results are therefore likely due to the increased insulin dosage on top of the aforementioned impact of red blood cell life span. However, more studies are needed to investigate HbA1c reduction during pregnancy and its correlation with glycemic control.

Our study has some limitations. First, a relatively small cohort was enrolled, although it exceeded the sample size calculated a priori. Moreover, several parameters were not recorded, such as the duration of diabetes, lipid profile, and/or continuous glucose monitoring data, which set a limit on the in-depth evaluation of a number of factors. In addition, height was not recorded in several women, making impossible the calculation of BMI for the entire cohort. However, one of the inclusion criteria for this study was normal weight, and, therefore, women with overweight, obesity, or underweight were not initially enrolled. Furthermore, physical activity and dietary habits were not directly monitored and only self-reported, possibly creating bias. In addition, insulin resistance could equally occur during pregnancy in healthy subjects; in this regard, comparing patients with T1DM to women without gestational diabetes is not optimal. However, it was our decision to compare our study group with a healthy control group and to exclude women with gestational diabetes, since, in this case, the diagnosis occurs later (at least at 16–18 weeks of gestation or even at 24–28 weeks of gestation) and, therefore, we could not compare the baseline characteristics having different times of diagnosis. Furthermore, the mechanisms by which variations in body weight could exist are very different among women with and without T1DM and the therapeutic approach would vary widely. Finally, the time in range, which is now considered an important parameter for monitoring diabetes in pregnancy, was not recorded.

Our study also features some strengths. As a single-center study, all women underwent the same counseling given by the same health professionals, significantly limiting heterogeneity both in the assessment and in the management of the patients. Moreover, the population was relatively homogeneous in terms of ethnicity, age, education, and habits, contributing to a more solid interpretation of the results.

Pregnancy care in women with diabetes is very complex and should be dealt with by a multidisciplinary team involving diabetologists, gynecologists, and obstetricians, as well as registered dietitians. It is, moreover, crucial to provide mothers with the skills to cope with issues concerning their pregnancy, as their education can play a significant role in improving pregnancy outcomes. To address the issue by simply increasing insulin doses is to ? grossly underestimate the problem, while more attention should be paid to diet and physical activity in the effort to achieve body weight control in the management of pregnant women with T1D.

Pregnancy care in women with diabetes is extremely complex. To address the issue by simply increasing insulin doses is to grossly underestimate the problem. Instead, it should be dealt with by a multidisciplinary team involving diabetologists, gynecologists, and obstetricians, as well as registered dietitians. It is, moreover, crucial to provide mothers with the skills to cope with issues concerning their pregnancy, as their education can play a significant role in improving pregnancy outcomes. Finally, pregnant women with T1D must be encouraged to pay close attention to diet and physical activity to enable them to achieve body weight control during this critical period.