Complications
Maternal hypertension frequently complicates GDM. Routine assessments of BP and urinary protein are warranted.[23] Preeclampsia is also increased in GDM, and risk is related to increasing maternal glucose levels.
Treatment for GDM may reduce the risk for preeclampsia and hypertensive disorders in pregnancy.[67][68]
Risk increases with poor maternal glucose control.[67]
Risk of hypoglycemia increases with degree of maternal hyperglycemia, especially during labor. A case-control comparison found hypoglycemia in 5% of neonates delivered to mothers with GDM versus <1% of controls.[25] Intrapartum glycemic monitoring and control are warranted.
Prevalence is increased three- to fourfold and complicates 10% to 20% of pregnancies with diabetes involvement.[25]
GDM increases risk of hyperbilirubinemia to approximately 17%, a rate about double that in nondiabetic controls.[25]
Hypocalcemia was documented in almost 5% of pregnancies complicated by GDM, a rate about double that of controls without diabetes.[25]
Pregnancies of women with fasting hyperglycemia and poor glycemic control are at greater risk.[94] Risk is not likely to be increased in women with GDM that is well controlled with diet alone. Risk of serious perinatal complications, including fetal demise, was reduced by treatment in a randomized trial.[134]
A meta-analysis (involving >5 million women and >100,000 events) demonstrated that individuals with GDM have a twofold higher risk of future CVD events within the first decade postpartum.[132] The relationship between GDM and CVD was not solely attributable to type 2 diabetes because even after excluding those who developed type 2 diabetes, GDM was associated with more than a 1.5-fold higher risk of CVD.[132] Another meta-analysis found that GDM was associated with increased risks of overall and type-specific (coronary artery disease, myocardial infarction, heart failure, angina pectoris, cardiovascular procedures, stroke, and ischemic stroke) cardiovascular and cerebrovascular diseases that could not be solely attributed to conventional cardiovascular risk factors or subsequent diabetes.[133] The increased risk of CVD associated with GDM may be due to clustering of CVD risk factors in individuals with GDM, including overweight/obesity, dyslipidemia, and hypertension.[69] Emerging epidemiologic data highlight the importance of identification of subclinical CVD with coronary calcium scoring in individuals with a GDM history. However, the exact frequency of screening for CVD risk factors and type of diagnostic testing (e.g., laboratory and/or imaging markers) to be done postpartum remains to be defined.[69]
In utero exposure to GDM increases the risk of glucose intolerance, overweight or obesity, metabolic syndrome, and higher blood pressure in the offspring later in life.[24] The Hyperglycemia and Adverse Pregnancy Outcome (HAPO) follow-up study that evaluated 4832 offspring at a mean of 11.4 years postpartum showed that the prevalence of obesity was significantly higher in children of women with GDM (diagnosed at 28 weeks of pregnancy) compared with those without, with an adjusted odds ratio of 1·58 (95% CI 1.24 to 2.01).[135] Furthermore, the HAPO study showed a continuous and independent association between maternal glucose concentrations during pregnancy and greater adiposity and risk of impaired glucose tolerance in the offspring.[136][137] It also highlighted the importance of maternal weight status in pregnancy as a strong risk factor for childhood excess adiposity, confirming other observational studies.[24][138] It has been postulated that this intergenerational risk of excess adiposity and dysglycemia could be due to shared genetics, shared familial environment, or to programming due to an intrauterine metabolic environment created by excess glucose.[24] It remains unclear whether treatment of GDM can reduce the long-term risk of metabolic complications in offspring.[24]
Hypoglycemia frequently complicates the therapy of insulin-treated patients and is usually of mild severity.[128] Insulin-treated patients are educated on how to avoid, recognize, and treat hypoglycemia.
GDM recurs in 30% to 84% of subsequent pregnancies.[22] The wide range in recurrence rate is influenced by the variability of formal retesting in subsequent pregnancies.
The majority of women with GDM eventually develop type 2 diabetes, but diabetes can be delayed through lifestyle modification or metformin.[124][125][127][129][130] Women with prior GDM should be counseled about healthy lifestyle measures.[1] Metformin is not approved for prevention of diabetes, but it is recommended as a potential option for prevention of progression to type 2 diabetes in those with a history of gestational diabetes mellitus found to have prediabetes.[1] Patients with a history of GDM require close monitoring for the development of type 2 diabetes.[1][131]
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