DM and pregnancy

Gestational diabetes now includes both gestational impaired glucose tolerance and gestational diabetes mellitus (1).

• approximately 700,000 women give birth in England and Wales each year, and up to 5% of these women have either pre-existing diabetes or gestational diabetes
  • of women who have diabetes during pregnancy
    • estimated that 87.5% have gestational diabetes - which is defined as the development of diabetes during pregnancy (which may or may not resolve after pregnancy),
    • 7.5% have type 1 diabetes
    • the remaining 5% have type 2 diabetes
    • prevalence of type 1 diabetes, and especially type 2 diabetes, has increased in recent years
    • incidence of gestational diabetes is also increasing as a result of higher rates of obesity in the general population and more pregnancies in older women
      
      
• diabetes in pregnancy is associated with risks to the woman and to the developing fetus. Miscarriage, pre-eclampsia and preterm labour are more common in women with pre-existing diabetes. In addition, diabetic retinopathy can worsen rapidly during pregnancy. Stillbirth, congenital malformations, macrosomia, birth injury, perinatal mortality and postnatal adaptation problems (such as hypoglycaemia) are more common in babies born to women with pre-existing diabetes

NICE (2) suggest testing criteria for gestational diabetes as:

• use the 2-hour 75 g oral glucose tolerance test (OGTT) to test for gestational diabetes in women with risk factors (see below)
  
  
• offer women who have had gestational diabetes in a previous pregnancy:
  • early self-monitoring of blood glucose or
  • a 75 g 2-hour OGTT as soon as possible after booking (whether in the first or second trimester), and a further 75 g 2-hour OGTT at 24-28 weeks if the results of the first OGTT are normal
    
    
• offer women with any of the other risk factors for gestational diabetes a 75 g 2-hour OGTT at 24-28 weeks (see below)
  
  

• glycosuria detected by routine antenatal testing

  • be aware that glycosuria of 2+ or above on 1 occasion or of 1+ or above on 2 or more occasions detected by reagent strip testing during routine antenatal care may indicate undiagnosed gestational diabetes. If this is observed, consider further testing to exclude gestational diabetes

• risk factors for gestational diabetes:
  • BMI above 30 kg/m2
  • previous macrosomic baby weighing 4.5 kg or above
  • previous gestational diabetes
  • family history of diabetes (first-degree relative with diabetes)
  • minority ethnic family origin with a high prevalence of diabetes
    
    
• diagnosis of gestational diabetes
  • diagnose gestational diabetes if the woman has either:
    
    
    • a fasting plasma glucose level of 5.6mmol/litre or above or
      
      
    • a 2-hour plasma glucose level of 7.8mmol/litre or above

Before insulin was available, the perinatal mortality associated with diabetes approached 50%. Over the last 60 years, this horrific figure has been reduced to 2% in the best units. Nevertheless perinatal mortality amongst the babies of diabetics is still several times higher than amongst the general population and so continued attention must be paid to the well being of these patients through pregnancy.

At 6 weeks or more postpartum, diabetes UK suggest that a further oral glucose tolerance test should be undertaken in women diagnosed with gestational diabetes (whether or not the patient still has impaired glucose tolerance or impaired fasting glycaemia). These women, whatever the result of the oral glucose tolerance test, are at an increased risk of developing diabetes later in life.

• advice from the UK National Screening Committee on antenatal screening for diabetes..click here

NICE however suggest that (2)

• women who were diagnosed with gestational diabetes should be offered lifestyle advice (including weight control, diet and exercise) and offered a fasting plasma glucose measurement (but not an oral glucose tolerance test) at the 6-week postnatal check and annually thereafter

comparison of oral hypoglycaemic agents and insulin

• a systematic review concluded that there was no substantial maternal or neonatal outcome differences found with the use of glyburide or metformin compared with use of insulin in women with gestational diabetes (3)

The management of women with diabetes (Type 1 or Type 2) who become pregnant is described in the linked items in the menu below.

Reference:

• (1) Diabetes UK. Recommendations for the management of pregnant women with diabetes (including gestational diabetes). 2003
• (2) NICE (February 2015). Diabetes in pregnancy: management of diabetes and its complications from preconception to the postnatal period
• (3) Nicholson W et al. Benefits and risks of oral diabetes agents compared with insulin in women with gestational diabetes: a systematic review.Obstet Gynecol. 2009 Jan;113(1):193-205