Re: Gestational diabetes: new criteria may triple the prevalence but effect on outcomes is unclear
We thank Dr Hodson for his comment on our paper about overdiagnosis of gestational diabetes (GDM) and agree that women should be given choice about the need for intervention. However, terms fraught with emotion such as stillbirth and “risk of her baby dying” are inappropriate in this setting and unhelpful to the debate.
Firstly let us correct some factual errors. The ACHOIS study showed an increased risk of the baby being admitted to the special nursery in the treated group and not decreased1 as Dr Hodson states. Population studies and the other major intervention trial show no increased risk of stillbirth with GDM2-6. The ACHOIS study with 5 vs 0 stillbirth/neonatal deaths in the untreated vs treated groups is clearly at odds with other studies, and at least two of the 5 deaths could not plausibly be related to GDM (lethal congenital anomaly, intrauterine growth restriction)1. Dr Hodson details the improved outcomes seen with treatment in the MFMU study but these were all secondary outcomes:- treatment did not change the primary composite outcome6. Finally, and most importantly, both randomized controlled trials1;6 used a two-step process for the diagnosis of GDM, something that the newly proposed international criteria suggest dropping – a procedural change that fuels a huge increase in GDM prevalence.
The proposed criteria will double or triple GDM prevalence by capturing women with lower levels of glycaemia than those in the randomized controlled trials. Dr Hodson advocates a recipe for overdiagnosis: “treating larger groups of women for relatively smaller benefit”. We disagree. As there is no evidence that women diagnosed by the newly proposed criteria will benefit, but ample evidence that interventions and costs will increase, we consider it inappropriate to adopt them. A more rational and less emotional approach to the definition and management of GDM seems desirable.
Reference List
(1) Crowther CA, Hiller JE, Moss JR, McPhee AJ, Jeffries WS, Robinson JS. Effect of treatment of gestational diabetes mellitus on pregnancy outcomes. N Engl J Med 2005; 352(24):2477-2486.
(2) Shand AW, Bell JC, McElduff A, Morris J, Roberts CL. Outcomes of pregnancies in women with pre-gestational diabetes mellitus and gestational diabetes mellitus; a population-based study in New South Wales, Australia, 1998-2002. Diabet Med 2008; 25(6):708-715.
(3) Karmon A, Levy A, Holcberg G, Wiznitzer A, Mazor M, Sheiner E. Decreased perinatal mortality among women with diet-controlled gestational diabetes mellitus. International Journal of Gynaecology & Obstetrics 2009; 104(3):199-202.
(4) Fadl HE, Ostlund IK, Magnuson AF, Hanson US. Maternal and neonatal outcomes and time trends of gestational diabetes mellitus in Sweden from 1991 to 2003. Diabet Med 2010; 27(4):436-441.
(5) Ohana O, Holcberg G, Sergienko R, Sheiner E. Risk factors for intrauterine fetal death (1988-2009). J Matern Fetal Neonatal Med 2011; 24(9):1079-1083.
(6) Landon MB, Spong CY, Thom E, Carpenter MW, Ramin SM, Casey B et al. A multicenter, randomized trial of treatment for mild gestational diabetes. N Engl J Med 2009; 361(14):1339-1348.
Rapid Response:
Re: Gestational diabetes: new criteria may triple the prevalence but effect on outcomes is unclear
We thank Dr Hodson for his comment on our paper about overdiagnosis of gestational diabetes (GDM) and agree that women should be given choice about the need for intervention. However, terms fraught with emotion such as stillbirth and “risk of her baby dying” are inappropriate in this setting and unhelpful to the debate.
Firstly let us correct some factual errors. The ACHOIS study showed an increased risk of the baby being admitted to the special nursery in the treated group and not decreased1 as Dr Hodson states. Population studies and the other major intervention trial show no increased risk of stillbirth with GDM2-6. The ACHOIS study with 5 vs 0 stillbirth/neonatal deaths in the untreated vs treated groups is clearly at odds with other studies, and at least two of the 5 deaths could not plausibly be related to GDM (lethal congenital anomaly, intrauterine growth restriction)1. Dr Hodson details the improved outcomes seen with treatment in the MFMU study but these were all secondary outcomes:- treatment did not change the primary composite outcome6. Finally, and most importantly, both randomized controlled trials1;6 used a two-step process for the diagnosis of GDM, something that the newly proposed international criteria suggest dropping – a procedural change that fuels a huge increase in GDM prevalence.
The proposed criteria will double or triple GDM prevalence by capturing women with lower levels of glycaemia than those in the randomized controlled trials. Dr Hodson advocates a recipe for overdiagnosis: “treating larger groups of women for relatively smaller benefit”. We disagree. As there is no evidence that women diagnosed by the newly proposed criteria will benefit, but ample evidence that interventions and costs will increase, we consider it inappropriate to adopt them. A more rational and less emotional approach to the definition and management of GDM seems desirable.
Reference List
(1) Crowther CA, Hiller JE, Moss JR, McPhee AJ, Jeffries WS, Robinson JS. Effect of treatment of gestational diabetes mellitus on pregnancy outcomes. N Engl J Med 2005; 352(24):2477-2486.
(2) Shand AW, Bell JC, McElduff A, Morris J, Roberts CL. Outcomes of pregnancies in women with pre-gestational diabetes mellitus and gestational diabetes mellitus; a population-based study in New South Wales, Australia, 1998-2002. Diabet Med 2008; 25(6):708-715.
(3) Karmon A, Levy A, Holcberg G, Wiznitzer A, Mazor M, Sheiner E. Decreased perinatal mortality among women with diet-controlled gestational diabetes mellitus. International Journal of Gynaecology & Obstetrics 2009; 104(3):199-202.
(4) Fadl HE, Ostlund IK, Magnuson AF, Hanson US. Maternal and neonatal outcomes and time trends of gestational diabetes mellitus in Sweden from 1991 to 2003. Diabet Med 2010; 27(4):436-441.
(5) Ohana O, Holcberg G, Sergienko R, Sheiner E. Risk factors for intrauterine fetal death (1988-2009). J Matern Fetal Neonatal Med 2011; 24(9):1079-1083.
(6) Landon MB, Spong CY, Thom E, Carpenter MW, Ramin SM, Casey B et al. A multicenter, randomized trial of treatment for mild gestational diabetes. N Engl J Med 2009; 361(14):1339-1348.
Competing interests: No competing interests