Gestational diabetesO24.4

In 1824, the German physician H. Bennewitz described diabetes mellitus in pregnancy for the first time as part of a dissertation (Sweeting 2022).

In 1873, J. M. Duncan recognized that diabetes mellitus made pregnancy more difficult (Lende 2020).

Williams published the first diagnostic criteria for GDM in the United States in 1909 (Sweeting 2022).

In 1910, it was proposed that pregnant women with glucosuria be divided into two groups:

- Pregnant women with true (persistent) glucosuria.

- Pregnant women with glucosuria that occurred only after consumption of large amounts of sugar and starch (Lende 2020).

The first glucose load test with 50 g glucose was described in 1932. However, it was not until 1946 that the adverse effects of pregnancy on carbohydrate metabolism were documented by Hurwitz et al.

O' Sullivan was the first to regularly study pregnant patients with an oral 50 g- glucose solution in 1961 (Lende 2020).

The pathophysiological changes of the pancreas during pregnancy and lactation were first described by Claus Hellerström in 1963 (Lende 2020).

The WHO first recommended a 50- or 100-g glucose screening test in pregnant women in 1965. The thresholds were the same as those for non-pregnant diabetics (Sweeting 2022).

Since 2009, WHO recommends 75 g glucose load test in all pregnant women during 24-28 weeks gestation (Metzger 2010).

The first definition of gestational diabetes (GDM) came from the WHO in 1965 and was described as a "hyperglycemia of diabetic values during pregnancy" (Sweeting 2022).

Nowadays, GDM is understood to be a severe glucose tolerance disorder that first occurs during pregnancy (Herold 2022).

Hyperglycemia in pregnant women is nowadays divided into two different categories by the IADPSG (International Association of the Diabetes and Pregnancy Study Groups):

- overt diabetes (diabetes mellitus in pregnancy).

- GDM (Sweeting 2022)

GDM is a relatively common pregnancy complication (Plows 2018), Sweeting (2022) even calls it one of the most common complications during pregnancy.

GDM occurs in approximately 10% of all pregnant women with increasing prevalence (Herold 2022).

At low risk are pregnant women:

- who are < 25 years old

- with a BMI < 25 kg / m²

- without evidence of

- a macrosomia

- a maternal GDM

- a diabetes mellitus in 1st-degree relatives

- An ethnic group of, for example, African American, Hispanic, Native American (Kasper 2015), and Caucasian women, who have the lowest risk (Schäfer- Graf 2018).

Pregnant women in particular are at high risk of developing GDM,

- who have already been affected by GDM

- with increasing age of the pregnant women

- low level of education (3 x as often)

- Pregnancy of male fetuses (4 % higher risk)

(Schäfer- Graf 2018)

- PCO syndrome (polycystic ovary syndrome)

- Drug therapy with glucocorticoids or antipsychotics (Sweeting 2022)

In GDM, there is partly a genetic predisposition for both insulin resistance and insulin secretion disorder, which exists due to impaired beta cell function. This is significantly influenced by environmental factors and lifestyle (especially obesity) (Schäfer- Graf 2018).

The pathophysiology of GDM largely corresponds to that of type 2 diabetes mellitus and - as in the latter - is not fully understood (Schäfer-Graf 2018).

Causally, GDM probably involves a chronic, already pre-conceptional reduction in insulin sensitivity (Schäfer- Graf 2018), which is triggered by beta-cell dysfunction (Plows 2018). This is exacerbated by physiological insulin resistance from the 20th SSW onwards and can then only be compensated for inadequately (Schäfer- Graf 2018).

GDM usually manifests itself after the 20th week of gestation (Herold 2022). The 75 g glucose test should therefore be performed between 24 + 0 SSW and 27 + 6 SSW (Schäfer-Graf 2018).

GDM is usually asymptomatic (Stalla 2007). Otherwise, symptoms may exist that are also present in other forms of diabetes mellitus such as:

- fatigue

- reduced performance

- polyuria

- Polydipsia etc. (Herold 2022).

The diagnosis can be made after as little as a single pathologic 75 g oral glucose tolerance test (Herold 2022).

Oral glucose tolerance test (oGTT)

According to the GBA decision, the 75 g test must be preceded by a 50 g glucose screening test. However, since the 50 g test shows only questionable validity, this test is explicitly not recommended by the professional societies (Schäfer-Graf 2018).

In the 75 g glucose tolerance test, BG is determined from venous plasma under standardized conditions and quality-assured glucose measurement. The test is considered positive if the BG shows the following values:

- fasting ≥ 92 mg / dl (5.1 mmol / l)

- after 1 h ≥ 180 mg / dl (10.0 mmol / l)

- after 2 h ≥ 153 mg / dl (8.5 mmol / l)

(Schäfer- Graf 2018)

A single pathological value is sufficient to establish the diagnosis of GDM (Herold 2022).

- HbA1c- test

The concentration of HbA1c decreases from the beginning of conception with a nadir in the 2nd trimester.

Although the Hb1Ac test has a much lower sensitivity than the 75g test, it is very useful in detecting pre-existing and previously undiagnosed diabetes mellitus and should therefore also be performed in pregnant women. From a value of 5.9 - 6.5 % (40 - 48 mmol / mol), the additional performance of an oGTT is recommended (Schäfer-Graf 2018).

- MODY- DM (Maturity- onset- Diabetes of the Young)

(Herold 2022)

Complications for the mother may include:

- urinary tract infection

- increased risk of developing preeclampsia

- hydramnios

- premature birth

- necessity of a sectio (Herold 2022)

- periodontitis

- Candida infections

- Pregnancy-induced hypertension

- Depression during pregnancy (Schäfer- Graf 2018).

Postpartum, there is a higher risk for:

- cardiovascular disease at a younger age (Schäfer- Graf 2018).

Complications for the child may include:

- increased prenatal mortality

- increased perinatal morbidity (Herold 2022)

- polycythemia (Kasper 2015)

- Macrosomia with asymmetrically enlarged body parts or organs.

- Embryofetopathia diabetica with a birth weight of > 4,500 g

- the risk for the following diseases in the newborn are increased:

- respiratory distress syndrome

- hyperbilirubinemia

- polyglobulia

- shoulder dystocia

- postpartum hypoglycemia

- hypocalcemia

- Hypomagnesemia, etc (Herold 2022).

Long-term consequences for the child may include:

- Increased risk of obesity (Schäfer- Graf 2018).

Affected patients should first receive extensive education (Herold 2022). Lifestyle changes, management of maternal weight gain, and appropriate physical activity can treat up to 70-85% of patients with GDM (Lende 2020).

If diet and exercise are not sufficient to adjust BG appropriately, insulin therapy or insulin pump is recommended. Oral antidiabetic agents are contraindicated in pregnant women - according to pivotal studies (Herold 2022), as potential long-term effects in newborns have not been adequately studied to date (Lende 2020).

Insulin therapy:

Since pregnant women show a change in insulin sensitivity during pregnancy, the following should be observed during insulin therapy:

- during the 8th - 12th week there is an increasing insulin sensitivity and thus the risk of hypoglycemia increases

- in the 2nd half of pregnancy up to about the 36th week, insulin sensitivity decreases

- immediately after delivery, insulin sensitivity increases and the dose should be significantly reduced

- Breastfeeding phase:

- in nursing mothers the insulin requirement decreases by approx. 5 I. E.

- breastfeeding reduces the risk of diabetes for mother and child (Herold 2022)

The treatment goal is

- Fasting BG: 65 - 95 mg / dl

- 1- h- postprandial: < 140 mg / dl

- 2- h- postprandial: < 120 mg / dl

- before bedtime: 90 - 120 mg / dl

- between 2 - 4 o'clock at night: > 60 mg / dl

- normal HbA1c (Herold 2022)

In the majority of patients, GDM disappears after the end of pregnancy. However, there is a 50% risk of also developing GDM if the pregnancy recurs (Herold 2022).

The risk of developing permanent type 2 diabetes mellitus in Germany is >10% within the next 10 years (Herold 2022). In the USA, the risk is as high as 40% according to Kasper (2015).

If the expectant mother is optimally adjusted, infant mortality is < 1% and thus corresponds to that of healthy expectant mothers (Herold 2022).

To detect postnatal diabetes mellitus in the mother at an early stage, it is recommended to perform an oGTT at least every 3 years (Herold 2022).

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