Diabetes, Women's Health, Infant and Children | October 27, 2015 | Author: The Super Pharmacist
Gestational diabetes mellitus (GDM) is a term for diabetes which starts for the first time during pregnancy. Epidemiologically, GDM occurs in between 1 in every 20 to 50 of all pregnancies, usually starting in the second half of pregnancy (1).
GDM poses similar risk in pregnancy to those who have known diabetes, such as difficulties with giving birth and a greater chance of needing a caesarean section (2). Most women recover from GDM soon after pregnancy but there are high recurrent rates in future pregnancies, as well as an increased risk of developing diabetes at some point in the future.
There are a number of risk factors for developing GDM such as high BMI before pregnancy, previously unexplained stillbirths, short intervals between pregnancies, women who have had previous babies with very high birth weights (above 4.5kg), women with immediate family members who have diabetes, and women from particular ethnic groups. Women of South Asian, Black Carribean and Middle Eastern heritage have all been evidenced to be at a higher than average risk of developing GDM (3).
Diagnosis for GDM remains contested among health professionals as there is no clear agreement at present on diagnostic criteria (4).
Current guidelines recommend that GDM be diagnosed if they have fasting plasma glucose level of 5.6 mmol/L or above, or a 2 hour plasma glucose level of 7.9mmol/L or above (5).
As a general rule, most health professionals generally consider GSM to be any degree of glucose intolerance or high levels of blood glucose (hyperglycaemia) first recognised during pregnancy (7).
Good glycaemic control, has been evidenced in a number of studies to reduce serious perinatal morbidity and improve the mother’s health related quality of life (8,9,10). Mothers who are diagnosed with GDM will generally receive routine antenatal care with additional monitoring of blood glucose levels and routine monitoring of HbA1c.
Most treatments for GDM revolve around lifestyle modification and are non-drug based. This usually involves advice around healthy eating.
For mothers who have a BMI > 27 being offered a structured weight loss programme is important.
Physical acitivity for at least 30 minutes per day is encouraged, more for health benefits - as relatively little specific evidence is available regarding its help in preventing GDM or pregnancy glucose intolerance.
A systematic review by The Cochrane Collaboration, undertaken in 2012, covered 5 studies that evaluated the effect of exercise programmes on over 1200 mothers and found no conclusive evidence of positive effects. The review concluded that larger, better designed randomised trials are needed to better assess the effects of exercise on preventing GDM and other measures such as large-for-gestational age and perinatal mortality (11). A further Cochrane Review undertaken in 2013, investigating the impact of clinical management of pregnant women with borderline GDM, found that dietary advice or counselling and blood glucose level monitoring helps reduce the incidence of babies being born that are macrosomic (larger than 4.5kg, or 8lbs 13oz, at birth) (12). Whilst there remains relatively little evidence for non-medical interventions for mothers with borderline GDM, their non-invasive nature and focus on improving levels of physical activity and healthy lifestyle choices show no evidenced side effects of harm to either mother or unborn child.
In order to monitor the growth and wellbeing of the unborn child, women with GDM will also receive an additional foetal scan at 20 weeks for the detection of any foetal structural abnormalities and further monitoring every 4 weeks between 28-36 weeks.
When lifestyle measures and changes are not successful in maintaining glycaemic control during pregnancy, insulin is generally considered to be the gold standard treatment for hyperglycaemia. Studies have shown that where insulin is contraindicated in mothers with GDM, some oral hypoglycaemic agents can also be used as safe, effective and acceptable alternatives (13).
The course of action and drug use of choice will be determined by a number of different clinical and personal factors relating to plasma glucose levels, baseline levels of health, and complications such as macrosomia or hydraminos (an excess of amniotic fluid in the amniotic sac).
Treatment outcomes for GDM are generally good, although the risk of GDM in future pregnancies is high, with a 2 in 3 chance of recurrence (15). As such, mothers who are diagnosed with GDM are usually offered an annual HbA1c test, or advice around the early self-monitoring of glucose levels.
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2. Dunman NB (2015) Frequency of gestational diabetes mellitus and the associated risk factors Pak J Med Sci 31(1):194-7
3. Janevic T, Borrell LN, Savitz DA, Echeverria SE, Rundle A (2014) Ethnic enclaves and gestational diabetes among immigrant women in New York City Soc Sci Med 120:180-9
4. Hartling L, Dryden DM, Guthrie A et al (2014) Diagnostic thresholds for gestational diabetes and their impact on pregnancy outcomes: a systematic review. Diabet Med 31(3):319-31
5. Diabetes in pregnancy: management of diabetes and its complications from preconception to the postnatal period NICE Clinical Guideline (February 2015)
6. Use of Glycated Haemoglobin (HbA1c) in the Diagnosis of Diabetes Mellitus (2011) World Health Organization
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14. Langer O, Conway DL, Berkus MD, Xenakis EM, Gonzales O (2000) A comparison of glyburide and insulin in women with gestational diabetes mellitus N Engl J Med 19:343(16):1134-8
15. Nohira T, Kim S, Nakai H, et al (2006) Recurrence of gestational diabetes mellitus: rates and risk factors from initial GDM and one abnormal GTT value. Diabetes Res Clin Pract 71(1):75-81