Response to Comment on: Chakera et al. Antenatal Diagnosis of Fetal Genotype Determines if Maternal Hyperglycemia due to a Glucokinase Mutation Requires Treatment. Diabetes Care 2012;35:1832–1834

Diabetes Care, Jan 2013

Ali J. Chakera, Victoria L. Carleton, Beverley Shields, Glynis P. Ross, Andrew T. Hattersley

A PDF file should load here. If you do not see its contents the file may be temporarily unavailable at the journal website or you do not have a PDF plug-in installed and enabled in your browser.

Alternatively, you can download the file locally and open with any standalone PDF reader:

https://care.diabetesjournals.org/content/36/1/e15.full.pdf

Response to Comment on: Chakera et al. Antenatal Diagnosis of Fetal Genotype Determines if Maternal Hyperglycemia due to a Glucokinase Mutation Requires Treatment. Diabetes Care 2012;35:1832–1834

0 Department of Diabetes and Endocrinology 1 Peninsula College of Medicine and Den- tistry, University of Exeter , Exeter , U.K.; the - W Tartaglia et al. (1) in response to e appreciate the comments by our study. We agree with Tartaglia et al. that maternal glucose management in glucokinase (GCK) pregnancy should be guided by knowledge of whether the fetus has inherited the mutation from the mother. In our article (2), we propose that fetal genetic testing should be performed if chorionic villus sampling (CVS) or amniocentesis is performed for another reason. Amniocentesis/CVS cannot be recommended as a routine procedure in the management of pregnant women with GCK mutations, as the 1% miscarriage rate is unacceptably high and outweighs the potential benefits of knowing fetal GCK genotype. At present, fetal growth on ultrasound is used as a surrogate marker for fetal GCK status with increasing growth seen when the fetus has not inherited the mutation. Tartaglia et al. raise a valid point that the optimal cutoff is unclear, especially given uncertainty in measurements. If the fetus does not inherit the GCK mutation, maternal hyperglycemia results in an approximately sixfold increase in macrosomia, with mean increase in corrected birth weight of 700 g, ;1 SD difference (3). Using data from Hindmarsh et al. (4), we estimate that if the abdominal circumference exceeds the 75th percentile, the odds ratio that the child is unaffected is increased by 3.5-fold. If the abdominal circumference exceeds the 90th percentile, this odds ratio increases to sevenfold. The variability in measurement will determine the confidence limits around these estimates, but this will be reduced if repeated measures are used. For this reason we suggest having two values over the 75th percentile in scans separated by 2 weeks before starting insulin. One advantage of this cutoff is that it has an evidence base to support it because Buchanan et al. (5) used this cutoff in a randomized controlled trial. Ultimately, noninvasive prenatal diagnosis (6) will replace the need to make an indirect assessment based on ultrasound and result in individualized care for pregnant women with GCK mutations. ALI J. CHAKERA, MBCHB1,2 VICTORIA L. CARLETON, MBBS3,4 BEVERLEY SHIELDS, PHD1 GLYNIS P. ROSS, MBBS3 ANDREW T. HATTERSLEY, DM1,2 c c c c c c c c c c c c c c c c c c c c c c c c References 1. Tartaglia E, Iafusco D, Giuliano P, et al. Com ment on: Chakera et al. Antenatal diagnosis of fetal genotype determines if maternal hyperglycemia due to a glucokinase mutation requires treatment. Diabetes Care 2012;35: 18321834 (Letter). Diabetes Care 2013;36: e14. DOI: 10.2337/dc12-1364 2. Chakera AJ, Carleton VL, Ellard S, et al. Antenatal diagnosis of fetal genotype determines if maternal hyperglycemia due to a glucokinase mutation requires treatment. Diabetes Care 2012;35:18321834 3. Spyer G, Macleod KM, Shepherd M, Ellard S, Hattersley AT. Pregnancy outcome in patients with raised blood glucose due to a heterozygous glucokinase gene mutation. Diabet Med 2009;26:1418 4. Hindmarsh PC, Geary MP, Rodeck CH, Kingdom JC, Cole TJ. Intrauterine growth and its relationship to size and shape at birth. Pediatr Res 2002;52:263268 5. Buchanan TA, Kjos SL, Montoro MN, et al. Use of fetal ultrasound to select metabolic therapy for pregnancies complicated by mild gestational diabetes. Diabetes Care 1994;17:275283 6. Lo YM. Fetal nucleic acids in maternal blood: the promises. Clin Chem Lab Med 2011;50:995998 (...truncated)


This is a preview of a remote PDF: https://care.diabetesjournals.org/content/36/1/e15.full.pdf

Ali J. Chakera, Victoria L. Carleton, Beverley Shields, Glynis P. Ross, Andrew T. Hattersley. Response to Comment on: Chakera et al. Antenatal Diagnosis of Fetal Genotype Determines if Maternal Hyperglycemia due to a Glucokinase Mutation Requires Treatment. Diabetes Care 2012;35:1832–1834, Diabetes Care, 2013, pp. e15-e15, 36/1, DOI: 10.2337/dc12-1497