SCREENING AND DIAGNOSIS
Objectives • At the end of this session you will be able to: – – – –
Define GDM Identify the risks for development of GDM. State the prevalence of GDM locally Explain the reason for identifying and treating GDM – Identify appropriate screening measures – Identify who should be screened – Identify diagnostic criteria
Definition • Glucose intolerance with onset or first recognition during pregnancy • Characterized by β-cell function that is unable to meet the body’s insulin needs
Buchanan, Wiang, Kjos, Watanabe 2007
Glucose regulation during pregnancy • Insulin resistance begins in mid pregnancy and progresses through the third trimester – A result of maternal adiposity and effects of placental hormones
• β -cells usually make more insulin to compensate for resistance – when they cannot meet the needs hyperglycemia occurs
• GDM represents a state of chronic βcell dysfunction in the face of insulin resistance • Insulin resistance and insulin levels are different prior to pregnancy in women who develop GDM and those who do not • Changes in insulin sensitivity are similar in both groups during pregnancy • However in GDM women, insulin secretion does not increase adequately Buchanan, Wiang, Kjos, Watanabe 2007
Prevalence • The prevalence of GDM is estimated to be 1016.9% in pregnant women depending on the diagnostic criteria used. • Prevalence also varies by region and ethnicity. • Highest prevalence is in South East Asia • Lowest in North America and the Caribbean
• Prevalence higher – in less physically active women. – In older women – In women with higher BMI – In those with a strong family history of diabetes WHO, 2013 IDF, 2013
Discussion • What are the risk factors for gestational diabetes? • What risk factors do you see most often in your setting?
Risk factors for GDM High risk
Low risk
• Obesity • Diabetes in 1st degree relative • Previous • history of GDM or glucose intolerance • complicated pregnancy • infant with macrosomia > 3.5 kg • Older age • High risk ethnic group; South Asian, East Asian, Indigenous American or Australian, Hispanic • PCOS
• Age less than 25 years • No previous poor pregnancy outcomes • No diabetes in 1st degree relatives • Normal prepregnancy weight and weight gain during pregnancy • No history of abnormal glucose tolerance
Perkins, Dunn, Jagastia, 2007
Is Hypertension a risk factor? • Hypertension prior to pregnancy or during 1st trimester – doubled the risk of GDM – independent of maternal weight • Hence all women with hypertension should be screened for GDM
Hedderson, Ferrara, 2008
Why diagnose and treat GDM? • Short term risks for the mother – Development of gestational hypertension, worsening essential hypertension or development of preeclampsia – Operative delivery - related to macrosomia – Polyhydramnios – Premature labour
• Long term risks for the mother – Development of type 2 diabetes in next ~10 years (30-60% depending on population) – Development of cardiovascular disease CDA, 2013 Metzger, Buchanan, et al. 2007
Why diagnose and treat GDM? • Short term risks for the baby – Macrosomia – Neonatal hypoglycemia – Jaundice – Preterm birth – Birth injury – Hypocalcemia/ hypomagnesimia – Respiratory distress syndrome
• Long term risks for the baby – Obesity – Type 2 diabetes
Importance of follow up • Long term follow up studies have shown that most women with GDM will develop diabetes within the first decade after the pregnancy • Testing after pregnancy is important - more about this later
Kim, Newton, Knopp 2002
Screening - Whom to screen - When to screen - How to screen
Who to screen Some guidelines recommend screening all women at the first visit to rule out preexisting type 2 diabetes
Most guidelines recommend screening all women for GDM at 24-28 weeks gestation.
ADA, 2015 CDA , 2013
When to screen? First trimester
• Screening in 1st trimester - to rule out unidentified pre-existing diabetes • Fasting plasma glucose >126 mg/dl (7 mmol/L) or • HbA1c >6.5% or • Random >200mg/dl (11.1 mmol/L) or • 2hr value in OGTT >200mg/dl (11.1 mmol/L) • If overt diabetes is detected, it must be treated appropriately. ADA, 2015
When to screen Screening for GDM
• Screening should be done at 24-28 weeks • Diagnosis based on a 75 gm glucose load given in fasting state • GDM diagnosed when one or more of the following is present • Fasting 92 - 125 mg/dl (5.0 – 6.9 mmol/L) • 1 hour post 75 gm load >180 mg/dl (10 mmol/L) • 2 hour post 75 gm load >153mg/dl (8.5 mmol/L) • If woman tests negative, screening at 32 weeks also may be necessary in presence of high risks World Health Organization, 2013
Diagnostic criteria WHO (2013) 1 or more
IADPSG 1 or more
ADA “one step”
ADA “two step”
Fasting plasma glucose
5.1-6.9 mmol/L (92-125 mg/dl)
>5.1 mmol/L (92 mg/dl)
>5.1 mmol/L (92 mg/dl)
1 hour PG after 75gm load
>10.0mmol/L (180mg/dl)
>10.0mmol/L (180mg/dl)
>10.0mmol/L (180mg/dl)
50-g glucose load (nonfasting) If 1 hour > 7.8mmol/L (140mg/dl) –
2 hour PG after 75gm load
8.5-11.0 mmol/L (153199 mg/dl)
>8.5 mmol/L (153 mg/dl)
>8.5 mmol/L (153 mg/dl)
Diabetes Care 2015, WHO 2013
Do 100 g OGTT GDM If 2 of 4 results high
How to screen Key considerations for screening in low resource countries • • • • • •
Low cost No requirement for elaborate preparation High sensitivity and specificity Short turn-around time Be administered by health workers with minimal training Need little maintenance, calibration, or refrigeration
Agarwal et al, 2007
Venous or capillary The venous plasma is the gold standard Where laboratory facilities or technicians are not available, capillary glucose estimations may be done using a hand held glucose meter. The glucose meter must be standardized with a lab and calibrated against the lab on a regular basis.
Which of these women has GDM? All have had 75g glucose load at about 25 weeks – Rupinder, overweight, 35 years old, • fasting 90 mg/dl (5.0 mmol/L), • 1 hr 170mg/d (9.4 mmol/L), • 2hr 135mg/dl (7.5 mmol/L)
– Joanne, 3rd pregnancy, history of big babies, – fasting 130 mg/dl (7.2 mmol/L), – 1 hr 190mg/dl (10.5 mmol/L) – 2 hr 220mg/dl (12.2 mmol/L)
– Maria, 1st pregnancy, 25 years old, obese, – fasting 90mg/dl (5 mmol/L), – 1 hr 168mg/dl (9.3mmol/L) – 2 hr 160 mg/dl (8.8mmol/L)
Giving the diagnosis Will my baby be ok? – 1st question often asked Is this temporary? – 2nd question Questions provide an opportunity for teaching • Must answer truthfully • Must convey importance of management during pregnancy for healthy outcome but also for future health of baby and mother Risk of type 2 diabetes Risk of obesity
References American Diabetes Association. Clinical Practice Recommendations 2015. Diabetes Care. 2015;38(1) Agarwal et al - Fasting plasma glucose as a screening test for gestational diabetes mellitus, Archives of Gynecology and Obstetrics 2007 Buchanan T, Xiang A, Kjos S, Watanabe R. What is gestational Diabetes? Diabetes Care 2007;30(2):S105-111. Canadian Diabetes Association Clinical Practice Guidelines Expert Committee. Canadian Diabetes Association 2013 Clinical practice guidelines for the prevention and management of diabetes in Canada; Diabetes and pregnancy. Can J of Diabetes. 2013;37(suppl 1):S168-183. Hedderson MM, Ferrara A. High blood pressure before and during early pregnancy is associated with an increased risk of gestational diabetes mellitus. Diabetes Care. 2008;31(12):2362-2367. IDF Diabetes Atlas 6th Ed, 2013 Kim C. Newton KM, Knopp RH. Gestational diabetes and the incidence of type 2 diabetes. Diabetes Care 2002;25:1862-1868 Metzger BE, Buchanan TA, Coustan DR, De Leiva A, Hadden DR, Hod M. Summary and recommendations of the fifth international workshop-conference on gestational diabetes mellitus, Diabetes Care. 2007;30(suppl 2):S251-260. Perkins JM, Dunn JP, Jagastia SM. Perspectives in gestational diabetes mellitus: A review of screening, diagnosis and treatment. Clinical Diabetes. 2007;25(2):57-62 WHO. Diagnostic Criteria and Classification of Hyperglycaemia First Detected in Pregnancy , 2013