Pregnancy Diabetes. Gestational Diabetes Mellitus (GDM): Prevention, Screening, and Therapy


Pregnancy Diabetes. Gestational Diabetes Mellitus (GDM): Prevention, Screening, and Therapy

Part II

Diagnosis and therapy guidelines for Gestational Diabetes Mellitus(GDM)

German Diabetes Society Evidence-Based Guidelines for Diagnostics, Therapy, and Aftercare


Gestational Diabetes is one of the most common complications in pregnancy (Germany, about 10% affected women)! Therefore, every pregnant woman should participate in the screening for prevention - and thenalready in the first third of pregnancy (between 24 and 28 weeks of pregnancy), the sugar metabolism should be examined by the doctor. In high-risk groups (overweight or obesity or other indications of metabolic syndrome) should be investigated earlier – as early as the 20th week of pregnancy.

In Germany, the screening is required by law, and it is noted in the mother's pregnancy passport, but in many complication cases, the examination was too late or not done at all; thus, the early diagnosis was missed. 

Metabolic syndrome (to be investigated in case of obesity!) is one of the main risks for the development of gestational diabetes mellitus (GDM)

A Metabolicsyndromeis a sign of a significantly increased risk of Diabetes (it is therefore referred to as prediabetes). The symptoms of this are the constellation of overweight orobesity (especially with increased abdominal fat percentage), increased blood pressure, increased blood lipid levels, and reduced carbohydrate metabolism (reduced insulin sensitivity or increased insulin resistance).  

If the woman is already affected before pregnancy, increasing insulin resistance can be observed in her already from the 20th week of pregnancy; this corresponds to a relative insulin deficiency, disturbs the carbohydrate metabolism, and a vicious cycle with an increasingly poor metabolism develop (Kautzky 1997).


 Kautzky-Willer A. et al. Pronounced Insulin Resistance and Inadequate ß-cell Secretion Characterize Lean Gestational Diabetes During and After Pregnancy Diabetes Care, 1997 /20;11

 For insulin resistance and insulin secretion disorder, there is partly a genetic predisposition. However, the clinical symptoms appear in different forms and after other course times because of lifestyle factors, accelerating or inhibitory influences (epigenetic influences). The typical accelerating factors are the adverse diet ("fast carbs" and high-calorie diets, i.e., also due to too much fat intake) and too little physical activity. This result - mutually reinforcing the excessive body fat percentage (overweight or obesity) and the disturbed insulin metabolism. One also usually sees a disturbed fat metabolism (reduction of adiponectin and increase of leptin) and increased inflammatory messengers (inflammatory factors such as the TNF-αand various surrogate parameters for increased oxidative stress.

In addition to the signs of metabolic syndrome, one should also pay attention to diabetes-specific symptoms (urge polyuria, strong thirst polydipsia, higher sugar levels in the urine (test strip) glucosuria). Then it should be investigated immediately whether there is a yet undiscovered diabetes mellitus.

Other risks for developing gestational diabetes (GDM) exist in high-risk pregnancies, such as:

· women over 45 years of age

· women with a BMI over 30

· if pregnancy with Gestational Diabetes was already present in the past (risk of repetition)

· although previously there were already marginally increased blood sugar levels regardless of pregnancy

· if a child weighing more than 4500 g has already been born 

· if parents or brothers and sisters with diabetes occur in the pregnant woman's family

· if there is high blood pressure 

· vascular diseases such as coronary heart disease, peripheral circulatory disorder, or disturbance of internal circulation

 The risk of recurrence of gestational diabetes in further pregnancies (in our cultures in women of Caucasian origin) is 35-50%. For ethnic groups with a high risk of diabetes (e.g., in Asia, Australia, Latin America), the succession risk increases to 50-84%.  


Risk factors for the risk of recurrence of the gestational diabetes GDMare (in addition to the risks for the first occurrence):

· Obesity (BMI > 30), 

· Number of pregnancies * 

· Diabetes diagnosis before the 24th pregnancy week in previous pregnancies 

· necessary insulin therapy 

· distance of fewer than 24 months between pregnancies

· weight gain of more than 3 kg between pregnancies 

· increased fasting blood glucose two months postpartum 


*In women with GDM in the first pregnancy but not in the second pregnancy, the risk increased by 6.3 times in the third pregnancy (95% CI 4.5-9.0). In women with GDM in both pregnancies, the risk increased by 25.9 times

Blood glucose analysis from the vein blood – if necessary, after the oral glucose load test.

Diagnosis must be made based on blood glucose measurement from venous blood according to certified laboratory standards. The blood glucose measurement from capillary blood (e.g., from the finger pad or earlobe) and the measure with a blood glucose test strip tool is no longer permitted, as this is too inaccurate or defective.

Gestational diabetes is suspected if it is measured a fasting blood-glucose value above the standard value. The first suspicion arises when the fasting blood sugar level exceeds 92 mg/dl (5.1 mmol/l).  If this is the case, it is essential to make a second measurement on another day.

Gestational diabetes is diagnosed if blood glucose levels from 92-125 mg/dl (5.1-6.9 mmol/l) come out in early pregnancy.

With an HbA1c value ≤ 5.9%, manifest diabetes mellitus is unlikely, but early gestational diabetes can still be present. Therefore, an additional fasting blood glucose determination is necessary.

For HbA1c values of 5.9-6.4%, an oral glucose load test(oGTT) is recommended for further clarification. At HbA1cvalues ≥ 6.5% a diabetes is detected.


Control and therapy of gestational diabetes


After the mother and the child's father have been informed about the connections and risks, the necessary changes or optimization measures regarding lifestyle factors are discussed in detail and, if further specialists initiate feasible, longer-term training measures.

This concerns diet and physical activity topics and weight management  - targeted weight development (recommended limits of physiological weight gain during pregnancy). In addition, pregnant women should also be trained to carry out blood glucose checks themselves.

In case of persistent harmful levels, pharmacotherapy should be explained and initiated.


The frequency and timing of self-checks are continuously adjusted in individual cases to the effort and course of the therapy and to the measured results. 


The blood glucose self-measurement of pregnant women requires controls about the correct execution and also concerning the blood glucose home measuring system – both should be checked regularly. Pregnant women should be provided with appropriate diaries for documentation and guided to the correct documentation. 


Accompanying additional checks by the gynecologist

In addition to the checks of blood glucose levels and the correct measurements by the pregnant woman, the gynecologist checks other parameters and clarifies the further necessary therapy – including whether insulin therapy is indicated. This fact then requires further intensive training of pregnant women by trained experts (e.g., state-certified dietitians)


Lifestyle Improvement - Diet and Physical Activity

With the aim of nutrition, the criteria recommended in a balanced set of healthy foods apply.

Essentially, the fast-metabolizable carbohydrates must be avoided or at least significantly reduced (sweet drinks, sugar, sweets, white flour products, and possibly also potato and polished rice); also, high-calorie foods should be avoided. Plenty of vital and high-fiber foods should be balanced (this does not mean that all carbohydrates* should be avoided, but choose the slow metabolizable "slow carbs" in the right combination with protein-rich foods (low-fat light meat- poultry meat; fish and legumes, nuts and seeds), and valuable fatty acids (in particular the omega-3 fatty acids DHA and EPA from fish or alternative sources.


 * Dietary recommendations often provide such abstract information that the diet should contain 40-50% carbohydrates, 20% protein, and 30-35% fat; carbohydrates should not be less than 40% or 175g. 

This advice is not sufficient, as it does not yet allow quality characteristics (differences in carbohydrates and insulin effects to be recorded by the food combinations). Not simply 175g carbohydrates can be defined as a minimum quantity, as this does not cover differences in calorie requirements according to different body sizes and different physical activities. Such blanket and abstract statements can be very inadequate.


In terms of physical activity, endurance loads are most effective (e.g., faster walking – jogging). At least one hour per day should be targeted (this can also be divided into two units '30 minutes or three units a' then 25 minutes each). Any additional exercise is good, which is not too compressed or too unfamiliar to the pregnancy belly and causes discomfort. A physical activity tracker (smartphone or special smartwatch) is good. About 8000 to 10,000 steps a day should be sought. Increased physical activity as well as weight reduction (in case of obesity) should ideally be started at pregnancy planning and, if not possible, should be started at the latest in the first third of pregnancy, since it is only later that the habituation can be much more difficult.


  The Federal Institute for Agriculture and Nutrition (BLE) offers a lot of helpful recommendations and materials for healthy lifestyles via the homepage "Healthy in Life". You can also download a detailed publication (special issue with background information and literature sources and recommendations for action) on the topics of health promotion during pregnancy.  This special issue with the recommendations for action  is also available in English.

Prof. Dr. Werner Seebauer is Dean of Studies – Association of German Preventologists, Head of Preventive Medicine Department of Institute of Transcultural Health Sciences (European University Viadrina) and Head of Preventive Medicine – NESA (The New European Surgical Academy). Since 2000, prof. dr. Werner Seebauer worked only in preventive medicine, after ten years spent at the Frankfurt University Hospital. He is also involved in the medical professionals training for nutrition and prevention.