Objectives: This guideline reviews the evidence relating to the diagnosis and obstetrical management of diabetes in pregnancy. Outcomes: The outcomes evaluated were short and long-term maternal outcomes including pre-eclampsia, Caesarean section, future diabetes and other cardiovascular complications; and fetal outcomes including congenital anomalies, stillbirth, macrosomia, birth trauma, hypoglycemia and long-term effects. Evidence: Published literature was retrieved through searches of PubMed and The Cochrane Library using appropriate controlled vocabulary (MeSH terms "diabetes" and "pregnancy"). Where appropriate, results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. There were no date limits but results were limited to English or French language materials. Values: The quality of evidence was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care. Summary Statements: 1. The adverse outcomes associated with diabetes in pregnancy are substantially associated with hyperglycemia as well as the co-existing metabolic environment. Women with pre-existing diabetes should receive preconception care to optimize blood sugar control and other co-morbidities. Outcomes for the fetus/neonate and the mother in both pre-gestational diabetes mellitus and gestational diabetes mellitus pregnancies are improved by multidisciplinary management whose goal is achieving optimal blood sugar control and appropriate fetal surveillance (II-2). 2. Retrospective studies indicate that women with pre-gestational diabetes mellitus have an increased risk of stillbirth before 40 weeks of gestation when compared with the general obstetrical population. Similarly, large recent cohort and simulation studies of women with gestational diabetes mellitus pregnancies also indicate a higher risk of stillbirth between 36-39 weeks gestation (II-2). 3. Women with gestational diabetes mellitus have a higher risk of pre-eclampsia, shoulder dystocia, Caesarean section and large for gestational age infants (II-2). 4. Treatment of women with gestational diabetes mellitus and optimization of glycemic control reduces the risk of pre-eclampsia, shoulder dystocia, and large for gestational age infants (I). 5. The occurrence of gestational diabetes mellitus increases the risk of developing type 2 diabetes in the future for the mother (II-2). Recommendations: 1. The "preferred screening and diagnostic 2-step" approach for gestational diabetes mellitus of the Canadian Diabetes Association 2013 guidelines is endorsed. All pregnant women should be offered screening between 24-28 weeks using a standardized non-fasting 50-g glucose challenge screening test (GCT) with plasma glucose (PG) measured 1 hour later (III-B). 1.1. If the value is <7.8 mmol/L, no further testing is required. 1.2. If the value of the GCT is 7.8-11.0, a 2-hour 75-g oral glucose tolerance test with fasting PG (FPG), 1-hour PG, 2-hour PG should be performed. Gestational diabetes mellitus is diagnosed if 1 value is met or exceeded: i. FPG >= 5.3 mmol/L ii. 1-h PG >= 10.6 mmol/L iii. 2-h PG >= 9.0 mmol/L 1.3. If the value of the GCT is >= 11.1 mmol/L, gestational diabetes mellitus is diagnosed 2. The "alternative 1-step diagnostic" approach of the Canadian Diabetes Association 2013 guidelines is acceptable. In this strategy pregnant women should be offered testing between 24-28 weeks using a standardized 2-hour 75-g oral glucose tolerance test with fasting plasma glucose (FPG), 1-hour plasma glucose (PG), 2-hour PG (III-B). Gestational diabetes mellitus is diagnosed if 1 value is met or exceeded: i. FPG >= 5.1 mmol/L ii. 1-h PG >= 10.0 mmol/L iii. 2-h PG >= 8.5 mmol/L It is recognized that the use of different diagnostic thresholds for the "preferred" and "alternate" strategies could cause confusion in certain settings. Despite this the committee has identified the importance of remaining aligned with the current CDA 2013 guidelines as being a priority. It is thus recommended that each care centre strategically align with one of the two strategies and implement protocols to ensure consistent and uniform reporting of test results. 3. If there is a high risk of gestational diabetes mellitus based on multiple risk factors, screening or testing should be offered during the first half of the pregnancy and repeated at 24-28 weeks gestation if initially normal. If for any reason it was missed or if there is a clinical suspicion of later onset gestational diabetes, a screening or diagnostic test should be performed (II-2B). 4. Women with pre-existing or gestational diabetes mellitus should be provided with care by a multidisciplinary team aimed at attaining and then maintaining euglycemia (II-2B). 5. For patients with pre-gestational diabetes mellitus or gestational diabetes mellitus, starting at 28 weeks as a baseline, with subsequent serial assessment of fetal growth every 3-4 weeks is suggested to assess the effect of maternal glycemic control on fetal growth rate and amniotic fluid volume (II-2B). 6. Initiation of weekly assessment of fetal well-being at 36 weeks is recommended in pre-gestational diabetes mellitus and in gestational diabetes mellitus. It is also reasonable to consider weekly fetal assessment for women with diet controlled gestational diabetes mellitus beginning at 36 weeks. Acceptable methods of assessment of fetal well-being near term can include the non-stress test, non-stress test + amniotic fluid index, biophysical profile or a combination of the above (III-A). 7. If co-morbid factors are present such as obesity, evidence of suboptimal glycemic control, large for gestational age (>90%), previous stillbirth, hypertension or small for gestational age (<10%) are present, earlier onset and/or more frequent fetal health surveillance is recommended. In specific cases where fetal growth restriction is suspected, the addition of umbilical artery and fetal middle cerebral artery Doppler assessment may be helpful (II-2A). 8. Pregnant women with gestational diabetes mellitus or with pre-gestational diabetes mellitus should be offered induction between 3840 weeks of gestation depending on their glycemic control and other co-morbidity factors (II2-B). 9. Antenatal corticosteroid therapy should be administered to women with insulin-treated gestational diabetes mellitus and pregestational diabetic women at the same dosage, according to the same indications, and in the same gestational age range as that recommended for non-diabetic women (Skoll A, et al. No. 364-Antenatal Corticosteroid Therapy for Improving Neonatal Outcomes. J Obstet Gynaecol Can 2018;40:1219-39). When administered to women with preexisting or poorly controlled diabetes, close maternal glycemic surveillance is recommended (III-B). Following the first dose of betamethasone, the following insulin adjustments are recommended as per CDA guidelines (Diabetes Canada Clinical Practice Guidelines Expert C, et al. Diabetes and Pregnancy. Can J Diabetes 2018;42 Suppl 1:S255-S82): Day 1: Increase the night insulin dose by 25% Days 2 and 3: Increase all insulin doses by 40% Day 4: Increase all insulin doses by 20% Day 5: Increase all insulin doses by 10% to 20% Days 6 and 7: Gradually taper insulin doses to pre-betamethasone doses 10. If not previously done, in women with threatened preterm labour requiring betamethasone, a screening and diagnostic test for gestational diabetes mellitus should be performed either before or at least 7 days after the administration of betamethasone (III-B). 11. Women with GDM should be offered testing with a 75-g oral glucose tolerance test between 6 weeks and 6 months postpartum to detect prediabetes and diabetes (Thompson D, et al. Diabetes and pregnancy. Can J Diabetes 2013;37 Suppl 1:S168-83) (II-2A). 11.1 Normal i. Fasting plasma glucose (FPG) <6.1 mmol/L ii. 2h <7.8 mmol/L iii. HbA(1C) <6.0% 11.2 Pre-diabetic i. FPG 6.1-6.9 mmol/L or ii. 2h plasma glucose (PG) 7.8-11.0 mmol/L or iii. HbA(1C) 6.0-6.4% 11.3 Type 2 Diabetes mellitus i. FPG >= 7.0 mmol/L ii. Random PG or 2h PG >= 11.1 mmol/L iii. HbA(1C) >= 6.5% 12. 12. Breastfeeding is strongly recommended after delivery for all women with pre-gestational diabetes mellitus or gestational diabetes mellitus (II-2A).
