Diabetes during Pregnancy: Key Concepts and Diagnostic Criteria



Diabetes is a relatively common condition during pregnancy that affects approximately https://bootdiabetics.com/ According to the organization, this condition should not be trivialized due to its potential complications. It is also a subject that frequently appears in medical residency exams. Therefore, it is crucial to review the key concepts of diabetes during pregnancy to succeed in these exams.

Diabetes Mellitus

Diabetes Mellitus (DM) is a metabolic disorder characterized by abnormal blood glucose levels. It can occur due to defective production of insulin by beta cells in the pancreas (Type 1 DM) or peripheral resistance to insulin (Type 2 DM). In women, pregnancy can lead to the development of Gestational Diabetes Mellitus (DMG), caused by hormonal changes and increased insulin resistance.

The main risk factors for the development of DMG include advanced maternal age, overweight and obesity, family history of diabetes, personal history of metabolic disturbances, and obstetric history. Understanding these risk factors is essential for clinical practice during medical residency.

Development of Gestational Diabetes Mellitus

Most cases of DMG occur due to increased insulin resistance during pregnancy. This insulin resistance leads to higher maternal blood glucose levels and increased transport of glucose to the placenta. Between 24 and 28 weeks of gestation, insulin resistance reaches its peak, and if the pancreas is unable to produce enough insulin, hyperglycemia can develop, leading to the diagnosis of Gestational Diabetes Mellitus.

Symptoms and Diagnosis

DMG can be asymptomatic and is usually identified through screening tests. However, some symptoms may be present in pregnant women, such as increased thirst, frequent urination, fatigue, and blurred vision. It is important to differentiate these symptoms from normal physiological changes during pregnancy. The diagnosis of DMG is established through routine tests, including oral glucose tolerance test (OGTT) and fasting blood glucose levels.

Diagnostic Criteria

In Brazil, the diagnostic criteria for DMG are established based on fasting blood glucose levels and OGTT results. Fasting blood glucose levels below 92mg/dL are considered normal, while levels between 92 and 125 mg/dL indicate DMG. Fasting blood glucose levels higher than 126 mg/dL suggest pre-existing diabetes before pregnancy. Other criteria, such as HbA1c levels or random blood glucose tests, can also be used to diagnose pre-existing diabetes.

Diagnostic Flow Chart

The diagnostic flow chart for DMG depends on the timing of the first prenatal visit. If the first prenatal visit occurs after 20 weeks of gestation, an OGTT should be performed between 24 and 28 weeks without the need for fasting blood glucose levels. If the first prenatal visit occurs after 28 weeks, the OGTT should be performed immediately. However, the availability of OGTT may be limited in some cases, and in these situations, fasting blood glucose levels can be used as an alternative diagnostic test.

Management and Treatment

Once a diagnosis of DMG is confirmed, the main goal of treatment is to control blood glucose levels. This can be achieved through strict adherence to a nutritional therapy plan, regular physical activity, monitoring fetal movements, and frequent blood glucose monitoring. The target blood glucose levels are below 95 mg/dL in fasting state, below 140 mg/dL one hour after meals, and below 120 mg/dL two hours after meals.

In cases where lifestyle interventions fail to achieve glycemic control, pharmacological management is necessary. Insulin therapy is the most common treatment option, with intermediate-acting and fast-acting insulin being the preferred options. The initial dose is typically 0.5 units/kg/day, and insulin is usually administered during the morning due to the higher insulin resistance during this time of day. In severe hyperglycemia cases, Metformin can be used, although it is generally avoided in pregnant women.


Gestational Diabetes Mellitus is a common topic in medical residency exams and clinical practice. It is essential to understand the key concepts and diagnostic criteria to succeed in exams and provide appropriate care to pregnant women. Strengthening your theoretical knowledge through comprehensive study materials and individualized mentoring can greatly enhance your preparation for medical residency exams.



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