Diabetes has accompanied humanity for millennia and represents the epidemic of the third millennium. The term diabetes encompasses several metabolic diseases, all of which share hyperglycemia, caused by insufficient insulin secretion, its impaired action, or both. Chronic hyperglycemia leads to 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 (T2D); or adult-onset diabetes
- Type 1 diabetes (T1D); can be autoimmune or idiopathic
- Gestational diabetes (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 consequence of the higher incidence of obesity, more frequent occurrence of type 2 diabetes in women of reproductive age, and the decision to become pregnant later in life. However, DM in pregnancy poses a greater risk for complications in pregnancy for both the child and the mother. Women who had DM before pregnancy but it was not recognized have a higher risk of fetal malformations and spontaneous miscarriage, the possibility of developing and worsening chronic DM complications, and require regular follow-up and treatment even after pregnancy.
Fasting glycemic levels or those from a 75g oral glucose tolerance test (OGTT) reach permissible diagnostic values, but do not reach the glycemic levels that are criteria for diagnosing diabetes.
Pre-pregnancy DM is divided into:
- Type 2 DM;
- Type 1 DM;
- Other types of DM.
If DM was not known before conception, hypoglycemia discovered only during pregnancy may be a consequence of:
- GDM
- Pre-pregnancy DM that was not recognized before conception
- Type 1 DM that appeared during pregnancy.
To timely identify women with DM, the International Association of Diabetes and Pregnancy Study Groups (IADPSG) working group recommended screening for probable pre-pregnancy DM already at the first prenatal visit to the doctor. If tests were performed before conception, the incidence of malformations and spontaneous miscarriages associated with hyperglycemia would be lower. In Slovenia, these criteria have been used since 2011. Therefore, good glycemic control and strict regulation of blood sugar are important (UKC Maribor, 2012).
*Since 2012, the IADPSG criteria apply, where diagnostic glucose values for GDM are lower than in the previous Carpenter and Coustan criteria. Therefore, in Slovenia, we observed an increase in the incidence of GDM from 3.5% until 2011 to 7.5% in 2012. We can expect an incidence of up to 17% of all pregnancies.
If diabetes or GDM is not confirmed at the first examination, 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 assessment of glycemic status, pregnant women should be advised to consume food without dietary restrictions for the three days prior to testing and to approach the test after at least an 8-hour fasting period (during which they can only drink water, without any additives).
Approximately 0.3% of women who become pregnant in Slovenia have DM. We are talking about 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 but it was not recognized should not be categorized as GDM, as they have a higher risk of fetal malformations, spontaneous miscarriage, the possibility of developing and worsening chronic DM complications, and also require regular follow-up and treatment after childbirth, throughout their lives.
Slovenian guidelines recommend self-monitoring of blood glucose fasting, before main meals, and 90 minutes after them. If fasting glucose concentration or glucose before main meals is above 5.3 mmol/L, or after meals above 6.6 mmol/L, pharmacological treatment is introduced.
Hyperglycemia at conception and during organogenesis is teratogenic, causing cardiovascular abnormalities in neural tube development, caudal regression syndrome, and the aforementioned spontaneous miscarriages. Good glycemic control is important 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). At the birth of a fetus that is too large for its gestational age due to DM in pregnancy, shoulder dystocia, clavicle fracture, or Erb’s palsy of the newborn may occur. After birth, the fetus is at risk of hypoglycemia, hypocalcemia, and hyperbilirubinemia. Pregnant women with DM are 2-3 times more likely to deliver by C-section. The most common motive for planned C-section is to prevent hypoxic-ischemic brain damage that could occur during a complicated delivery, especially in a macrosomic child. There is no evidence for the benefit of routine completion of pregnancy by C-section, so it is decided only in cases of confirmed fetal macrosomia.
Optimal pregnancy management and proper postnatal care can reduce these risks.
GLYCEMIC CONTROL DURING LABOR
Vaginal delivery is equivalent to prolonged physical activity, so the need for insulin is reduced during it, regardless of the type of DM. This increases the risk of hypoglycemia during labor for the mother who was treated with insulin during labor. At the same time, preventing hyperglycemia in the mother is essential to prevent 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, typically 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, the decision to use insulin and glucose infusion during labor is made if glycemia cannot be maintained within the target range without it.
After delivery, the mother’s insulin requirement decreases, so those who were treated with insulin for pre-pregnancy DM must immediately reduce their insulin doses to pre-pregnancy levels and then adjust them according to measured blood glucose values. Those who were treated for GDM with anti-hyperglycemic drugs during pregnancy are advised to discontinue them immediately after delivery, as most no longer need them. For those who were treated for GDM, we measure fasting glucose levels 2-3 days after delivery. Glucose levels are measured again 6 weeks after delivery.
After childbirth, women are encouraged to establish breastfeeding as soon as possible, which inhibits the development of Type 1 and 2 DM in the child and the occurrence of Type 2 DM in the mother, and may reduce the risk of cardiovascular diseases and breast and ovarian cancer. Breastfeeding, appropriate weight gain, and a healthy lifestyle for the mother represent important prevention against metabolic syndrome and DM in the child.
Women usually also have diabetologist’s instructions with them.
Source:
Takač and Geršak et al. (2016). Gynecology and Perinatology, University of Maribor, Faculty of Medicine; first edition; Čokolič, Zavratnik, Steblovnik – Diabetes in Pregnancy; 533-43
UKC Mb (2012) – Pregnant Woman and Mother with Diabetes; Collection of Lectures
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