Volume 198 - Issue 11
Gestational diabetes needs to be managed
Authors: Michael C d’Emden, Narelle D Fagermo, Amanda J Love and Karin M C Lust
Med J Aust 2013; 198 (11): 595-596. || doi: 10.5694/mja13.10433
Published online: 17 June 2013
Published online: 17 June 2013
To the Editor: McIntyre and Oats1 suggest that Australian medical practitioners should adopt the new International Association of the Diabetes and Pregnancy Study Groups (IADPSG) diagnostic criteria for the management of gestational diabetes mellitus (GDM),2 mainly because of the findings of the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study.3 If adopted, a significant number of women will be diagnosed with GDM if their only blood ...
To the Editor: McIntyre and Oats1 suggest that Australian medical practitioners should adopt the new International Association of the Diabetes and Pregnancy Study Groups (IADPSG) diagnostic criteria for the management of gestational diabetes mellitus (GDM),2 mainly because of the findings of the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study.3 If adopted, a significant number of women will be diagnosed with GDM if their only blood glucose level (BGL) abnormality is a fasting BGL of 5.1–5.4 mmol/L. The quoted studies do not provide outcome data to confirm benefit at these levels.4,5 In addition, women currently diagnosed with GDM on the basis of a 2-hour BGL of more than 8.0 mmol/L but below the new IADPSG level of 8.5 mmol/L2 will no longer meet the criteria. But outcome data show a benefit of management at these levels.4 Also, the US study on treatment for mild GDM used a 100 g oral glucose tolerance test (OGTT)5 with a 2-hour BGL cut-off that approximates 8.0 mmol/L on a 75 g OGTT.6 Thus the two quoted outcome studies demonstrate benefit of treatment at BGLs that will no longer be accepted for the diagnosis of GDM.
The authors imply that the new criteria will not increase resource demand. The main abnormality in the quoted intervention studies was the postprandial BGLs, which are amenable to lifestyle change.4,5 The fasting BGL is less responsive, at least in the short term. It is likely that a significant number of women will require insulin based on these lower fasting BGLs. Consequently, a woman with a fasting BGL of 5.1 mmol/L will be diagnosed with GDM, and will potentially be treated with insulin to achieve the recommended fasting BGL of 5.0 mmol/L or less.2 Will a 0.1 mmol/L reduction in fasting BGL confer any clinical benefit?
The current guidelines7 are supported by outcome data demonstrating benefit from intervention. The HAPO study is hypothesis generating.3 What is required is an outcome study that randomly assigns women whose only abnormality on their OGTT is a fasting BGL of 5.1–5.4 mmol/L. Until that study is completed, the current guidelines should continue to be used.
Competing interests
No relevant disclosures.
References
- McIntyre HD, Oats JJN. Gestational diabetes needs to be managed. Med J Aust 2013; 198: 78-79. CHDBDBID
- Metzger BE, Gabbe SG, Persson B, et al. International Association of Diabetes and Pregnancy Study Groups Consensus Panel. International association of diabetes and pregnancy study groups recommendations on the diagnosis and classification of hyperglycemia in pregnancy. Diabetes Care 2010; 33: 676-682. i1142895
- HAPO Study Cooperative Research Group; Metzger BE, Lowe LP, Dyer AR, et al. Hyperglycemia and adverse pregnancy outcomes. N Engl J Med 2008; 358: 1991-2002. i1142897
- Landon MB, Spong CY, Thom E, et al; Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal–Fetal Medicine Units Network. A multicenter, randomized trial of treatment for mild gestational diabetes. N Engl J Med 2009; 361: 1339-1348. i1142899
- Crowther CA, Hiller JE, Moss JR, et al; Australian Carbohydrate Intolerance Study in Pregnant Women Trial Group. Effect of treatment of gestational diabetes mellitus on pregnancy outcomes. N Engl J Med 2005; 352: 2477-2486. i1142901
- Mello G, Elena P, Ognibene A, et al. Lack of concordance between the 75-g and 100-g glucose load tests for the diagnosis of gestational diabetes mellitus. Clin Chem 2006; 52: 1679-1684. i1142903
- Hoffman L, Nolan C, Wilson JD, et al. Gestational diabetes mellitus — management guidelines. The Australasian Diabetes in Pregnancy Society. Med J Aust 1998; 169: 93-97. i1142907