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How Carbohydrate Consumption Impacts Glycemic Control Among Pregnant Women With Type 1 Diabetes

Jul 22, 2017

Study focuses on quality and quantity of carb consumption during pregnancy.

Pregnant women with type 1 diabetes are at an increased risk of developing perinatal outcomes such as infant malformations and increased infant size for gestational age. Therefore, the need to obtain close to normal hemoglobin A1c levels prior to and during pregnancy is crucial in pregnant women with diabetes. Moreover, appropriate glycemic control throughout continuous daily monitoring parameters along with insulin treatment is warranted to promote positive outcomes. In addition, carbohydrate consumption both in quantity and quality of meals is one of the main dietary factors affecting glycemic control.


It is observed that most women with diabetes, particularly T1DM, gain more weight than recommended. An increase in gestational weight gain impairs fetal growth with and without diabetes. This increase in weight can be modified via adequate control on carbohydrate consumption before and during pregnancy. So long as appropriate dietary measures restricting large amounts of carbohydrates are in place, women with and without diabetes can improve their clinical outcomes drastically. In a recent study titled “The Influence of Carbohydrate Consumption on Glycemic Control in Pregnant Women With Type 1 Diabetes,” researchers proposed to study the influence of the quantity and quality of carbohydrate consumption on glycemic control in pregnant women with type 1 diabetes. Researchers attempted to study whether or not carbohydrate counting would benefit pregnant women with type 1 diabetes.

The retrospective study was conducted from January 2013 to December 2014, and was part of the routine care at the Center for Pregnant Women with Diabetes at Rigs Hospital. Pregnant women enlisted in the study were mailed a welcome letter along with a ‘diet-recording’ log sheet to complete 3 days prior to their first antenatal visit. Exclusion criteria included women with previous bariatric surgery, known celiac disease, and women with at least one day of diet recording. The study included 107 of the 171 women previously enrolled, who met inclusion criteria. During the first antenatal visit, a dietitian recorded each participant’s daily carbohydrate intake by incorporating carbohydrates with a high glycemic index using a glycemic index scale from 0 to 7. A score of 7 indicated that women consumed carbohydrates with a high glycemic index whereas scores of 0 indicated that the carbohydrates consumed were of low glycemic index sources. In addition, the dietitian also collected data on each participant’s knowledge of carbohydrate consumption by knowing almost nothing, knowing some, how to count carbohydrates but not using it in the consumption of carbohydrates, or using carbohydrate counting on a daily basis. Moreover, the number of snacks, meals, the number of hypoglycemic events, occurrence of ketonuria, and nausea were also documented. The main outcome in the study was HbA1c at the first antenatal visit, obtained via capillary blood samples using a DCA 2000 analyzer. Routine diabetes care was measured prior to and during early pregnancy by aiming HbA1c levels <7% and <6.5%, respectively. Women were grouped based on carbohydrate consumption (per 100g), the glycemic index score (0-7) and variations in daily carbohydrate consumption. These factors were used as exposure variables using a multiple linear regression analysis with HbA1c being the outcome variable. Tests performed were two-tailed and included a P value <0.05 to be statistically significant.

Results indicated that the mean age of participants was 32 years who have had diabetes for 15 years. The mean HbA1c among the participants was 6.7 at 64 gestational days. Moreover 71% of the women enrolled had HbA1c <7% at their first pregnancy visit and 43% had <6.5%. There was also 2 days of diet recording among 75% of participating women, with a mean carbohydrate consumption of 180g/day, where 61% of women consumed more than 175g/day. The glycemic index score was 2 on a scale of 0-3. After adjustment in daily insulin dose, there was a positive correlation between HbA1c and daily carbohydrate consumption (P=0.005). Moreover approximately 82% of women reported to having  knowledge of carbohydrate counting, and 45% of women using this method had lower HbA1c values (P=0.001), lower carbohydrate consumption (P=0.02), and a lower glycemic index (P=0.004). Women who consumed three snacks per day had a higher carbohydrate consumption than those counting carbohydrates (P=0.01), glycemic index of 0.5 vs. 2, and HbA1c levels of 6.6 vs. 6.7. Furthermore, hypoglycemic episodes varied among groups (P=0.11), as well as early gestational weight gain (2.3 vs. 1.6; P=0.007) and presence of ketonuria (P=1.00) was proportionate between women with and without nausea.

This study concluded that there was a positive correlation between HbA1c and the amount of carbohydrates consumed, among pregnant type 1 women. According to the American Institute of Medicine, it is imperative that pregnant women consume no more than 175g/day of carbohydrates to ensure a healthy pregnancy and fetal development. This study found that nearly 61% of women consumed more than 175g/day of carbohydrates. The presence of ketonuria may also negatively impact fetal development resulting in low cerebral function. However, reports of ketonuria were low in this study. In addition, adequate glycemic control is prudent in reducing excessive fetal growth. There was a positive association between glycemic index and HbA1c, however this did not continue after daily insulin doses were adjusted.

One limitation to this study was the exclusion of protein and fat intake, as well as physical activity. Other limitations beyond control included women neglecting to include unhealthy foods consumed, only recording healthy diets, and possibly under-reporting their calorie intake for the day. Moreover women who delivered at least one day of carbohydrate counting were included in the study. This may have served as bias to estimating carbohydrate consumption on a daily basis.

In conclusion, consuming lower amounts of carbohydrates on a daily basis helps lower glycemic index resulting in better glycemic control among pregnant women with type 1 diabetes.

Practice Pearls:

  • Poor dietary intake can negatively affect clinical outcomes in pregnant women with type 1 diabetes.
  • Adequate carbohydrate consumption ensures healthy pregnancies and fetal development.
  • Carbohydrates can affect glycemic control in pregnant women with type 1 diabetes.

Ásbjörnsdóttir, Björg, Cecelia E. Akueson, Helle Ronneby, Ane Rytter, Jens R. Andersen, Peter Damm, and Elisabeth R. Mathiesen. “The influence of carbohydrate consumption on glycemic control in pregnant women with type 1 diabetes.” Diabetes Research and Clinical Practice 127 (2017): 97-104. Web.

Roskjær, A. B., J. R. Andersen, H. Ronneby, P. Damm, and E. R. Mathiesen. “Dietary advices on carbohydrate intake for pregnant women with type 1 diabetes.” The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians. U.S. National Library of Medicine, Jan. 2015. Web. 12 July 2017.

Nuha Awad, Doctor of Pharmacy Candidate: Class of 2018; LECOM College of Pharmacy