Gestational diabetes mellitus and symptomatic diabetes mellitus – etiology, pathogenesis, and clinical manifestations.
GDM is glucose intolerance first recognized during pregnancy, usually in the second or third trimester.
Etiology (Causes)
- 1 Hormonal changes
- Increased levels of placental hormones (human placental lactogen, progesterone, estrogen, cortisol, prolactin).
- These hormones induce insulin resistance to ensure more glucose supply to the fetus.
- 2 Genetic and risk factors
- Obesity.
- Family history of diabetes.
- Advanced maternal age.
- Previous macrosomic baby (>4 kg).
Pathogenesis
- 1 Insulin resistance
- Placental hormones antagonize insulin action → decreased maternal insulin sensitivity.
- 2 β-cell dysfunction
- In susceptible women, pancreatic β-cells cannot compensate by increasing insulin secretion adequately.
- 3 Result: Hyperglycemia
- Leads to maternal and fetal metabolic disturbances.
Clinical Manifestations
- Often asymptomatic, detected by routine screening (oral glucose tolerance test at 24–28 weeks).
- Possible excessive fetal growth (macrosomia).
- Recurrent infections (e.g., candidiasis, UTIs).
- Polyhydramnios.
Fetal/neonatal complications
- Macrosomia → birth trauma.
- Neonatal hypoglycemia (due to islet cell hyperplasia).
- Respiratory distress syndrome.
- Increased risk of obesity and diabetes later in life.
Maternal complications
- Increased risk of preeclampsia.
- Higher risk of developing type 2 diabetes later.