Gestational Diabetes Mellitus (GDM): Screening and Management
Written by Dr. Muhammad Salar Raza · Manually reviewed by Dr. Muhammad Salar Raza · Content updated
Clinical Pathway
Screen all pregnant women at 24-28 weeks with a 75 g oral glucose tolerance test, or earlier when risk factors such as obesity or previous GDM exist. First-line management is medical nutrition therapy with structured physical activity and daily glucose self-monitoring. If fasting or postprandial targets are repeatedly exceeded despite lifestyle measures, start insulin, with metformin as an accepted alternative in many guidelines. Monitor fetal growth because GDM drives macrosomia, and plan delivery around 38-39 weeks when medication is required. After delivery, insulin needs fall sharply; arrange a 75 g OGTT at 6-12 weeks postpartum because about half of women with GDM later develop type 2 diabetes.
Clinical Reasoning
The diagnostic thresholds are fasting 92 mg/dL, 1-hour 180 mg/dL, and 2-hour 153 mg/dL on the 75 g OGTT, and a single abnormal value establishes the diagnosis. Lifestyle therapy succeeds in the majority, so jumping straight to insulin without a dietary trial is the classic wrong answer. Oral hypoglycemics such as glibenclamide and metformin cross the placenta to varying degrees, which is why insulin remains the pharmacological gold standard. Macrosomia raises the risk of shoulder dystocia and cesarean delivery, and neonatal hypoglycemia is the key immediate newborn complication to anticipate.
Sample MCQ
A 26-year-old woman at 27 weeks of gestation has a 75 g OGTT with fasting glucose 98 mg/dL and a 2-hour value of 160 mg/dL. She has no other medical problems. What is the most appropriate initial management?
- ADietary modification, exercise, and home glucose monitoring
- BImmediate basal-bolus insulin therapy
- CGlibenclamide as first-line drug therapy
- DNo action until after delivery
Correct Answer: Dietary modification, exercise, and home glucose monitoring
Her values exceed the diagnostic thresholds, confirming gestational diabetes, and first-line management is medical nutrition therapy with physical activity and structured glucose monitoring; most women reach targets without medication. Insulin is added only when glucose targets remain unmet after a lifestyle trial, so starting it immediately is premature. Glibenclamide crosses the placenta and is not first-line; metformin or insulin are the preferred pharmacological options when needed. Doing nothing exposes the fetus to macrosomia, shoulder dystocia, and neonatal hypoglycemia, and the mother to preeclampsia risk, so untreated GDM is never acceptable.
Guidelines and further reading
Related Clinical Topics
Diabetic Ketoacidosis (DKA): Diagnosis and Management
Diagnose DKA with diabetes or hyperglycemia, ketosis and metabolic acidosis; remember that SGLT2-associated DKA can occur without marked hyperglycemia. Start intravenous isotonic saline or balanced crystalloid, adapting the rate to hydration, cardiac and renal status. Check potassium before insulin: if potassium is below 3.5 mmol/L, replace it and delay insulin until potassium is above 3.5 mmol/L. Follow a monitored insulin and electrolyte protocol, adding dextrose as glucose falls so insulin can continue to clear ketones. Assess resolution using ketones and acid-base recovery rather than glucose or the anion gap alone. Treat the precipitant and overlap subcutaneous insulin before stopping the infusion.
Insulin Deficiency: Causes, Diagnosis and Management
Insulin deficiency is a metabolic condition characterized by inadequate production or complete absence of insulin from the pancreatic beta cells, resulting in impaired glucose utilization and elevated blood glucose levels. This typically leads to a diagnosis of Type 1 Diabetes Mellitus or represents a late stage of other pancreatic diseases. The mainstay of treatment is lifelong exogenous insulin replacement, administered through multiple daily injections or an insulin pump, to mimic physiological insulin secretion. Management also involves diligent blood glucose monitoring, carbohydrate counting, dietary adjustments, and regular physical activity to optimize glycemic control and prevent complications. Key symptoms include polyuria (frequent urination), polydipsia (excessive thirst), polyphagia (increased hunger), and unexplained weight loss. Patients often experience fatigue, blurred vision, recurrent infections, and in acute severe cases, symptoms of diabetic ketoacidosis such as nausea, vomiting, abdominal pain, and rapid, deep breathing (Kussmaul respirations).
Primary Hypothyroidism: Diagnosis and Management
Primary hypothyroidism is characterized by an underactive thyroid gland, resulting in decreased production of thyroid hormones. Common symptoms include fatigue, weight gain, cold intolerance, constipation, and dry skin. The diagnosis is established by finding an elevated Thyroid Stimulating Hormone (TSH) and a low free Thyroxine (Free T4). The standard treatment is daily replacement therapy with synthetic levothyroxine (T4). The goal of therapy is to normalize the serum TSH level, which should be rechecked 6-8 weeks after initiating or adjusting the dose.
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