Diabetes has accompanied humanity for millennia and represents the epidemic of the third millennium. The term diabetes covers several metabolic diseases, all of which share hyperglycemia resulting from insufficient insulin secretion, its impaired action, or both. Chronic hyperglycemia causes chronic damage, dysfunction, or even failure of various organs, especially the eyes, kidneys, nerves, heart, and blood vessels.
Classification of diabetes types
- type 2 diabetes (type 2 DM); or adult-onset DM
- type 1 diabetes (type 1 DM); can be autoimmune-mediated or idiopathic
- gestational diabetes mellitus (GDM); occurs during pregnancy
- other types of diabetes; resulting from medications, surgeries, infections, etc.
The number of women with diabetes (DM) in pregnancy (GDM) is increasing, which is a result of the higher prevalence of obesity, a higher incidence of type 2 diabetes among women of childbearing age, and the decision to have children later in life. DM in pregnancy represents a higher risk of complications for both the child and the mother. Women who had DM before pregnancy that went unrecognized face a higher risk of fetal malformations and miscarriage, the possibility of developing or worsening chronic DM complications, and require regular monitoring and treatment even after pregnancy.
Achieved fasting glycemia or results from a 75g oral glucose tolerance test (OGTT) reach permissible diagnostic values but do not reach the glycemia levels that serve as criteria for a diabetes diagnosis.
Pre-gestational DM is divided into:
- type 2 DM;
- type 1 DM;
- other types of DM.
If DM was not known before conception, hyperglycemia discovered only during pregnancy may be the result of:
- GDM
- pre-gestational DM that was not recognized before conception
- type 1 DM that appeared during pregnancy.
To ensure women with DM are identified in time, the International Association of Diabetes and Pregnancy Study Groups (IADPSG) working group recommended screening for the presence of probable pre-gestational DM at the very first prenatal doctor’s visit. If tests were performed before conception, the incidence of malformations and miscarriages associated with hyperglycemia would be lower. In Slovenia, these criteria have been used since 2011. Therefore, glycemic control and strict blood sugar management are important (UKC Maribor, 2012).
*Since 2012, IADPSG criteria have been in effect, where diagnostic glucose values for GDM are lower than in the previous Carpenter and Coustan criteria. Consequently, Slovenia saw an increase in GDM incidence from 3.5% until 2011 to 7.5% in 2012. An incidence of up to 17% of all pregnancies can be expected.
If diabetes or GDM is not confirmed at the first check-up, an OGTT test with 75g of glucose is performed between the 24th and 28th week of pregnancy. Since only proper preparation and execution of the OGTT allow for an accurate definition of glycemic status, pregnant women should be warned to eat without dietary restrictions for the last three days before testing and to approach the test after at least an 8-hour fasting period (during this period, they can only drink water, without any additives).
In Slovenia, DM affects about 0.3% of women who become pregnant. This refers to pre-existing diabetes (type 1 or type 2). A larger proportion of pregnant women (around 8% in 2012) develop gestational diabetes (GDM). Those who had DM before pregnancy that was not recognized should not be categorized as GDM, as they face a higher risk of fetal malformations, miscarriage, and the development or worsening of chronic DM complications, requiring regular lifelong monitoring and treatment even after childbirth.
Slovenian guidelines recommend self-monitoring of blood glucose while fasting, before main meals, and 90 minutes after them. If the glucose concentration is above 5.3 mmol/L while fasting or before main meals, or above 6.6 mmol/L after meals, medical treatment is introduced.
Hyperglycemia at conception and during organogenesis is teratogenic, causing cardiovascular abnormalities in neural tube development, caudal regression syndrome, and the aforementioned miscarriages. Good glycemic control is vital so that the child does not suffer consequences after birth.
In the last trimester of pregnancy, maternal hyperglycemia and fetal hyperinsulinemia create an unfavorable metabolic environment. At birth, the fetus is at risk of hypoxia and acidosis. Stillbirth is also more common (see table above). During the delivery of a fetus that is large for gestational age due to DM in pregnancy, shoulder dystocia, clavicle fracture, or Erb’s palsy of the newborn can occur. After birth, the fetus is at risk for hypoglycemia, hypocalcemia, and hyperbilirubinemia. Pregnant women with DM are 2-3 times more likely to give birth by C-section. The most common reason for a planned C-section is the prevention of hypoxic-ischemic brain damage that could occur during a complicated delivery, especially in a child with macrosomia. There is no evidence for the benefit of routine C-sections, so they are only chosen in cases of proven fetal macrosomia.
Optimal pregnancy management and proper postnatal care can reduce these risks.
GLYCEMIC CONTROL DURING CHILDBIRTH
Vaginal delivery is equivalent to prolonged physical activity, so the need for insulin is reduced during labor, regardless of the type of DM. This increases the risk of hypoglycemia during labor for a mother who was treated with insulin. At the same time, preventing maternal hyperglycemia is essential for preventing hypoglycemia in the newborn.
During labor, glycemia should therefore be maintained in the range of 4-7 mmol/L, which requires frequent blood glucose checks, usually every hour, and appropriate action.
Mothers with type 1 DM require a continuous infusion of insulin and glucose during labor. For mothers with type 2 DM and GDM, an insulin and glucose infusion is chosen if glycemia cannot be maintained within the target range without it.
After birth, the mother’s need for insulin drops, so those treated with insulin for pre-gestational DM must immediately reduce their insulin doses to pre-pregnancy levels and then adjust them according to measured blood glucose values. Those treated for GDM with antihyperglycemic medications are advised to stop them immediately after birth, as most no longer need them. For those treated for GDM, fasting glucose levels are measured on the 2nd or 3rd day after birth. Glucose levels are measured again 6 weeks after birth.
After birth, women are encouraged to establish breastfeeding as soon as possible, which inhibits the development of type 1 and 2 DM in the child and type 2 DM in the mother, and may reduce the risk of cardiovascular diseases, breast cancer, and ovarian cancer. Breastfeeding, appropriate weight gain, and a healthy maternal lifestyle represent important prevention against metabolic syndrome and DM in the child.
Usually, women also have instructions from their diabetologist with them.
Source:
Takač and Geršak et al. (2016). Gynecology and Perinatology, University of Maribor, MF; first edition; Čokolič, Zavratnik, Steblovnik – Diabetes in Pregnancy; 533-43
UKC Mb (2012) – Pregnant and Birthing Women with Diabetes; Collection of Lectures
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