Glucose Levels within Pregant Women with Type 1 Diabetes

By: Michael Callahan

Diet and nutrition require extra special attention during pregnancy. The foods eaten at this time are the baby’s main source of nutrients. According to the Academy of Nutrition & Dietetics, pregnant women should seek to consume a balanced diet, mostly made up of whole grains, fruits, vegetables, lean protein, low fat dairy, and healthful fats (ie: olive oil)1. This diet follows the general recommendations for eating a healthy, balanced diet, and aims to ensure key nutrients are being consumed. Getting proper nutrients is the primary goal during pregnancy. Another goal of consuming a diet rich in whole foods and avoiding high sugar/refined foods helps pregnant women to avoid unhealthy weight gain. A diet lacking in protein, iron, calcium, folic acid and other vitamins and minerals can be detrimental to the baby, as well as the mother. Paying close attention to diet, nutrition and overall health is important in all pregnant women to assure proper health of the mother and baby. Health components such as blood glucose levels are much more prone to fluctuation as the baby and mother are competing for nutrients. Babies born from women with diabetes or poor blood glucose control are at risk for birth defects. It is vital for women with diabetes prior to pregnancy to get blood glucose levels under control before and during pregnancy.           

High blood glucose levels pass through the placenta to the baby, and can contribute to birth defects 2. Ideally, it is important to get blood glucose levels under control before pregnancy even occurs. High blood glucose levels during the first trimester, can be detrimental to the baby, leading to risk of miscarriage and birth defects. This time period occurs seven weeks after the mother’s last period, at which point complete formation of the baby’s organs has occurred.


Diabetes is characterized by high blood sugar levels, also called hyperglycemia. Blood sugar or glucose, is synthesized in the muscle and liver, or obtained from the food we eat. It is our body’s main source of energy. Glucose travels through the blood to provide energy to all of our cells. Blood glucose levels are controlled by insulin, which is a hormone excreted by the pancreas in response to high blood glucose levels. Insulin’s role is to assist the blood in glucose transport to body cells, resulting in lower blood glucose levels.

Type 1 diabetes typically develops in younger people, and is also known as juvenile diabetes for this reason. Type 1 diabetes is characterized by insufficient insulin production. This is caused by the body’s immune system attacking and destroying the cells responsible for making insulin. Patients with type 1 diabetes require special attention. Insulin shots and oral medications are usually necessary to promote insulin levels. Diet, exercise, and monitoring and controlling blood pressure and cholesterol levels are also very important.

Type 2 diabetes, previously called adult-onset diabetes, affects people of all ages and is characterized by insulin resistance. This often happens in people who are overweight and/or inactive, and is typically a result of excess sugar intake. This causes the pancreas to pump out excess insulin in times of excess glucose levels. Over time, the added demand results in insufficient production of insulin by the pancreas when blood sugar levels do rise, causing hyperglycemia.

Women with type 1 and type 2 diabetes, should pay close attention to blood glucose levels three to six months prior to pregnancy if possible. It is not only essential to the health of the baby, but also for the mother to monitor blood glucose levels. Some possible risks for hyperglycemia or hypoglycemia in diabetic patients during pregnancy include urinary bladder or vaginal infection, worsening of diabetes symptoms related to kidneys and the eyes, and preeclampsia, which is high blood pressure (and sometimes protein in the urine). According to the American Diabetes Association, it is recommended to keep blood glucose levels between 60-199 mg/dl pre-meal, and 100-149 mg/dl post-meal during the first trimester2.

Another form of diabetes, known as gestational diabetes, occurs when women experience high blood glucose levels during pregnancy, who had not previously had blood glucose concerns. This is another reason to control blood glucose levels throughout the pregnancy process. Research is still being done to understand the cause of gestational diabetes, which as of 2014 has a prevalence of 9.2%, according to Centers for Disease Control and Prevention. Evidence supports the occurrence of gestational diabetes is most likely due to the hormones that support the placenta and growth of the baby. These hormones are also blocking the action of the mother’s insulin, thus causing insulin resistance. Due to the inability of the mother to produce enough insulin, blood glucose is taken from the blood and blood sugar levels rise. This process called hyperglycemia is what leads to gestational diabetes. Luckily, because gestational diabetes affects the mother during late pregnancy, the baby does not experience birth defects like those of mothers who had diabetes prior to pregnancy. Excess blood glucose still crosses the placenta however, causing the baby’s pancreas to produce more insulin to compensate for high blood glucose levels. The insulin is stored as excess fat, and babies born with excess insulin will ultimately be born with low blood sugar levels as a result. This leads to breathing problems and puts these babies at higher risk for obesity and type 2 diabetes later in life.


As mentioned earlier, the baby’s organs are forming during the first trimester. Therefore, it is vital for the mother to monitor blood glucose levels as soon as possible, ideally during pre-pregnancy. Women with type 1 and type 2 diabetes are at higher risk for health problems during and after pregnancy as well. Patients with type 1 diabetes need to prepare for the body’s elevated need for insulin, especially in the second and third trimester. The placenta creates hormones to facilitate the baby’s growth, but also blocks the mother’s insulin production. As a result, insulin needs increase, and should be discussed with a doctor prior to pregnancy. Monitoring blood glucose levels poses a particular problem for women with type 1 diabetes. These patients can experience substantial insulin level fluctuations on a day to day basis, making it difficult to maintain blood glucose levels within normal conditions. Even as patients are being closely monitored for blood glucose levels,are receiving intensive insulin therapy and controlled glycated hemoglobin levels (below 7%), over half the patients still have blood glucose levels above normal range. They typically also experience hypoglycemia, or low blood sugar, for up to 3.5 hours a day. Therefore, it is imperative to control not only hyperglycemia, at the expense of the baby’s health, but also hypoglycemia, at the expense of the mother’s health.

Glucose monitoring, insulin pumps, and sensor-augmented pump therapy are current tested methods used to safely get women with type 1 diabetes through their pregnancy. Due to advances in technology, a computer algorithm such as a closed-loop system, is being tested on mothers with type 1 diabetes to test its effectiveness. The closed-loop system contains a set of mathematical instructions that works synonymously with glucose levels of real-time glucose monitors. The algorithm works to adjust insulin-pump delivery based off of the glucose measurements received. In a particular study published by the New England Journal of Medicine, a closed-loop system was tested on patients with type 1 diabetes for at least 12 months 6. Stipulations regarding the patients included being between the age of 18 to 45, within a gestation period of 8 to 24 weeks, and a glycated hemoglobin level between 6.5 and 10%. These patients were already used to multiple daily injections, or an insulin pump. The closed-loop system relied on a constant reading of blood glucose levels from the patients and administered insulin via a pump every 12 minutes. Weight and total daily insulin dose administered were recorded daily. Through various randomized 4-week study trials, the effectiveness of the closed-loop system was assessed based off of time blood glucose concentrations were between 63 to 140 mg per deciliter (mg/dl) over night. Other considerations included recording and analyzing mean glucose levels, glucose variability, time spent in high or low blood glucose levels, insulin dose, and glycated hemoglobin levels. The results of the experiment showed a 15% increase in the percentage time that glucose was in the target range for over a 24 hour time period. Lower mean glucose levels were also achieved within this experiment. Most importantly, these results did not result in hypoglycemic levels in the patients, as insulin was distributed more evenly by use of the closed-loop system. Thus, a closed-loop system could be potentially beneficial to pregnant women with type 1 diabetes.

Monitoring nutrition and overall health throughout the pregnancy will be most beneficial for the mother and baby. Regardless of health status, the baby and mother are dependent on vital nutrients to fuel and energize this process. The health and safety of the mother and baby can be particularly challenging in type 1 diabetes patients. New technology, along with research and testing can give us a better understanding of ways to get mothers safely through pregnancy. The closed-loop system, for instance, yielded positive results. Diabetes research has helped us to understand it more than ever. A safe and healthy pregnancy is attainable, but it does take planning. The American Diabetes Association encourages type 1 diabetics to assemble a team of prenatal specialists to safely monitor the health of the mother1. Some of the specialists include: a dietitian, diabetes educator, as well as a doctor, obstetrician, and pediatrician with background knowledge in diabetes. All are available to provide knowledge, counseling and monitor health and wellness throughout the pregnancy.


  1. American Diabetes Association. (05, Nov. 2013). Before Pregnancy. American Diabetes Association. <;.
  2. Healthline Editorial Team. (30, Mar. 2016). Nutritional needs during pregnancy. University of Illinois-Chicago, College of Medicine. <;.
  3. Kohn, J. (07, Dec. 2015). Top tips for eating right during pregnancy. Academy of Nutrition & Dietetics. < expecting/eating-right-during-pregnancy>.
  4. Nichols, H. (2015). Diabetes, the difference between type 1 and type 2 diabetes. Medical News Today. <;.
  5. Stewart, Z. A., Wilinska, M. E. W., Hartnell, S., Temple, R. C., Rayman, G. Stanley, K. P.,…Murphy, H.R. (28, Aug. 2016). Closed-Loop Insulin Delivery during Pregnancy in Women with Type 1 Diabetes. New England Journal of Medicine: 375:644-654. <;.

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