Hyperglycemia and Pregnancy

Department of Obstetrics and Gynecology and Centre for Perinatal and Reproductive Medicine,
University of Perugia, Perugia, Italy
giancarlo.direnzo@unipg.it

• Hyperglycemia during pregnancy is related to an increased risk of unfavorable complications for the mother and infant: there is a need to screen pregnant women and apply preventive tools along with changes in lifestyle to ameliorate outcome.

Gestational hyperglycemia derives from different levels of glucose intolerance, arising or found for the first time during pregnancy. This definition includes also women with undiagnosed preexisting diabetes. So nowadays, the wider concept of “hyperglycemia in pregnancy” is more frequently used, referring to both diabetes with the first onset in pregnancy and diabetes diagnosed for the first time during pregnancy but with earlier onset.

The number of cases with gestational diabetes is rising worldwide due to the increase of specific risk factors, such as obesity, physical inactivity, over- and malnutrition, environmental pollution, and advanced maternal age.

The physiological insulin resistance during pregnancy is mainly due to the action of placental hormones, which is predominantly an insulin antagonist action. The main hormone involved in this mechanism is the placental lactogen hormone (HPL).

Under normal conditions, this new balance induces a compensatory increase in maternal insulin secretion to maintain a euglycemic state. Otherwise, if the additional production of maternal insulin is insufficient, hyperglycemia and consequently gestational diabetes develop.

Among the modifiable risk factors for gestational diabetes, maternal obesity (BMI >30) is a strong associated factor. Obesity, in fact, induces a maternal state of low-grade chronic inflammation due to the secretion of impaired adipokines. This inflammatory state, mainly due to the direct action of TNF-α on insulin receptors, causes a further reduction in insulin sensitivity.

The diagnosis of gestational diabetes (gestational hyperglycemia) is based on the oral glucose tolerance test (OGTT), where 75 g glucose are ingested in a single step. The test is carried out in pregnant women at 24– 28 weeks of gestation. In cases with important risk factors, such as a previous pregnancy with gestational diabetes or obesity, the patient is considered at high risk, and the test is recommended to be done precociously at 16–18 weeks of gestation.

Maternal and fetal/neonatal outcomes are directly correlated with the degree of maternal glycemic control. This can in some cases be achieved through a special diet and adequate physical exercise only, in some cases it is necessary to add an insulin therapy. The correct and effective management of these patients requires a multidisciplinary approach which includes the participation of gynecologist, diabetologist, nutritionist, midwife, and general practitioner [2].

A possible program for the prevention of gestational hyperglycemia can be based not only on physical exercise and diet, but also on the use of probiotics and inositols. A personalized diet combined with regular physical exercise should become part of the lifestyle of women planning to become pregnant, especially in women with important risk factors such as obesity.

In many studies, the use of inositols has been demonstrated to be a possible tool to modulate insulin sensitivity, also in pregnant patients affected by gestational diabetes or at a high risk to develop it (i.e. in obese patients). Myoinositol seems to be an insulin mediator, it has been related to insulin sensitivity both in animal models and in humans characterized by insulin resistance.

Very recently, the use of probiotics has been proposed as a possible preventive tool. They have been shown to be involved in numerous mechanisms. It seems that the effect of probiotics on glucose metabolism is attributable to their immunoregulatory properties; the regulation of inflammatory mechanisms, in fact, may be of particular importance for the fundamental role that inflammation plays in the process of insulin resistance. The change in the composition of intestinal microbiota through probiotics, i.e. changing the intestinal immunological environment, could be seen as a new tool for the regulation of glucose metabolism.
   
 

1. Hod M, Kapur A, Sacks DA, Hadar E, Agarwal M, Di Renzo GC, Cabero Roura L, McIntyre HD, Morris JL, Divakar H: The International Federation of Gynecology and Obstetrics (FIGO) Initiative on gestational diabetes mellitus: a pragmatic guide for diagnosis, management, and care. Int J Gynaecol Obstet 2015;131:S173–S211.
2. Hod M, Jovanovic LG, Di Renzo GC, De Leiva A, Langer O: Textbook of Diabetes and Pregnancy, ed 3. Boca Raton, CRC Press, Taylor and Francis Group, 2016.