Gestational diabetes increases the general risk of pregnancy

Author: Dr Sorin Ioacara | Last update: November 14th, 2020

A near-term pregnant woman is holding her belly in her hand, seen from the side, with a yellow dress on a background with slightly brown tall grass and intense sun.

Discover here: Diagnosis of gestational diabetes | Causes of gestational diabetes | Symptoms of gestational diabetes | Prevention | Duration of evolution | Metabolic changes | Risks for the child | Risks for the mother | Monitoring gestational diabetes | Treatment of gestational diabetes

Gestational diabetes is any abnormal increase in blood sugar first discovered in the 2nd or 3rd trimester of pregnancy. It is also known as pregnancy diabetes. Gestational diabetes occurs in about 3-5% of pregnancies. The percentage is lower at 20 years and higher after the age of 30. In many cases, it goes undiagnosed because it develops without symptoms, in a woman who often doesn’t show up for her regular investigations.

Diabetes discovered in the first trimester of pregnancy is not gestational diabetes. It is most often type 1 or type 2 diabetes. The criteria for diagnosing diabetes in the 1st trimester of pregnancy are those used outside of pregnancy.

Diagnosis of gestational diabetes

Several tubes of blood on a stand, slightly blurred and a box of cotton wool

Any fasting blood glucose ≥92 mg/dl (5.1 mmol/l) collected from the vein, starting with the 2nd trimester of pregnancy is diagnostic for gestational diabetes. The diagnosis cannot rely on values measured by a glucometer. Besides, current guidelines recommend that any pregnant woman perform an oral glucose tolerance test in the 24-28 week of pregnancy. This test consists of drinking 75g of glucose and measuring blood glucose values at three different moments:

  1. On an empty stomach – normal <92 mg/dl (5.1 mmol/l)
  2. One hour after ingestion of 75 g glucose – normal <180 mg/dl (10 mmol/l)
  3. Two hours after ingestion of 75 g glucose – normal <153 mg/dl (8.5 mmol/l)

You get a diagnosis of gestational diabetes if at least one of the three values is greater than or equal to the established threshold. For fasting (morning) blood glucose, the last typical figure is 91 mg/dl (5.1 mmol/l). Any value of 92 mg/dl (5.1 mmol/l) or more diagnoses gestational diabetes. Similarly, for blood glucose at one hour, the threshold is 180 mg/dl (10 mmol/l), and at two hours 153 mg/dl (8.5 mmol/l).

You should note that a single value greater than or equal to the established threshold is sufficient to diagnose gestational diabetes. The particular importance of any small glycemic rises on pregnancy complications is thus recognized.

Not every diabetes found in pregnancy is gestational diabetes

The diagnosis of gestational diabetes has undergone multiple changes over time. Before 2011, doctors didn’t exactly know the glucose thresholds from which the pregnancy complications start to rise.

Diabetes diagnosed in the first trimester of pregnancy is not considered gestational diabetes. This diabetes already existed before pregnancy, but the diagnosis revealed itself only in the first trimester of pregnancy. Most often, this newly discovered diabetes will fall into the category of type 1 or type 2.

Causes of gestational diabetes

The word "risk" written with neons on a wall

Not all women have the same risk of developing gestational diabetes. Each added risk factor will significantly increase the chances of its occurrence. Nowadays, many women choose to delay the time when they become pregnant. For this reason, the dangerous combination of older age and “slight” overweight is becoming increasingly common.

The main causes of gestational (pregnancy) diabetes are:

  • obesity before pregnancy
  • additional weight gain by week 24
  • mother’s age
  • previous birth of a child weighing more than 4.5 kg
  • history of gestational diabetes in an earlier pregnancy
  • history of polycystic ovary syndrome
  • history of high blood pressure
  • relatives with diabetes, mainly grade 1
  • family origins of people with a high frequency of diabetes (South Asia, the Caribbean, the Middle East)
  • glucocorticoid treatment in pregnancy
  • the presence of glucose in the urine

Symptoms of gestational diabetes

A tiger drinks water from a river.

Gestational diabetes is most often asymptomatic. Sometimes your blood sugar may rise high enough to cause signs and symptoms of high blood sugar. Most of these symptoms are somewhat usual during pregnancy. That’s why a woman doesn’t give them the importance they would have had outside of pregnancy. Hence, the absolute need for testing for gestational diabetes, starting with the 2nd trimester of pregnancy.

The main symptoms of gestational diabetes are:

  • dry mouth
  • thirst
  • often urination
  • fatigue
  • nausea
  • vomiting
  • urinary tract infections
  • visual disturbances

Prevention of gestational diabetes

a woman eats from a plate of healthy food

Women with one or more risk factors for gestational diabetes should actively participate in the prevention of its occurrence. It would be best if they followed a diet rich in fruits, vegetables and greens. These food categories should represent half of the food consumed at a meal. However, the amount of meat should be around 25% of a meal. The only recommended way to prepare this meat is by boiling. Finally, the remaining 25% of the food consumed at a meal can be potatoes, pasta or rice. There is a small additional benefit if you reduce these three food categories to less than 15% of the total amount of a meal. You may also want to increase the overall consumption of whole grains and skim milk products.

You may obtain additional benefits in the prevention of gestational diabetes by complying with your recommended sleeping hours. It would be best if you avoided conflict situations and stress in general. If you cannot avoid daily stress, you may try not to let it affect you too much emotionally.

Physical effort in the prevention of gestational diabetes

Physical effort must be daily, but within the tolerance of individual pregnant woman. In general, the number of steps recorded in a day on the phone should be over 10,000. The time allocated for medium-intensity physical exertion should be 30 minutes a day, five days a week.

It would help if you were careful when making medium intensity effort, always within your particular tolerance. By medium intensity effort in regnancy, we imply that the woman is at her limit for still breathing through her nose during the physical exercise. The need to breathe through your mouth to support the effort signals the need to take a break.

The duration of gestational diabetes

A sand hourglass next to a thick book and a flower, on a dark background

Pregnancy diabetes is a condition that can be “cured”. It is not necessarily a lifetime diagnosis, as with other forms of diabetes. However, even if gestational diabetes disappears after birth, it can reoccur at any time, including in a future pregnancy (50% chance). All women diagnosed with gestational diabetes should test themselves for the persistence of diabetes at 1.5-3 months after birth.

If you cannot do the testing for diabetes in the first three months after birth, it would be best you made every effort not to postpone beyond the first six months. The purpose is to determine the degree of alteration of carbohydrate metabolism persisting after birth. Testing for the persistence of diabetes after birth consists of one of the following three options:

  1. Fasting blood sugar
  2. Oral glucose tolerance test
  3. Glycosylated hemoglobin

It would be best if you examined the postpartum glucose metabolism status using the oral glucose tolerance test. The evaluation criteria will be those outside the pregnancy.

The discovery of a gestational diabetes that then disappears at birth is associated with an increased risk of developing type 2 diabetes later on during life. Hence, women who have had gestational diabetes should periodically test themselves for diabetes. The recommended testing frequency is 1-3 years, for the rest of their lives.

Metabolic changes in gestational diabetes

A young pregnant woman holds her belly in her hand, with pink-red flowers in her hand, seen from the side only at the level of the belly.

During pregnancy, the placenta makes sure that the fetus receives everything it needs. The hormones secreted by the placenta help the fetus to grow up healthy. However, some of these hormones are responsible for the mother’s resistance to insulin. Examples of such hormones are the placental growth hormone and placental lactogen hormone. Insulin resistance increases typically by 60% at the beginning of the 3rd trimester of pregnancy. Some hormones secreted by the mother, such as cortisol and TNFalfa, also contribute to this.

The mother’s body will find it increasingly difficult to use insulin. As a result, a progressively higher amount of glucose will be available to pass into the fetus’ body. The mother’s need for insulin can increase up to three times in these conditions.

Gestational diabetes occurs when the mother’s pancreas cannot produce all the insulin it needs during pregnancy. Insufficient amount of insulin leads to the accumulation of glucose in the mother’s blood. Consequently, there is an excessive glucose passage to the fetus. The glucose buildup in the mother’s blood leads to hyperglycemia and gestational diabetes.

Excess glucose available to the fetus

Excessive passage of glucose into the body of the fetus leads to stimulation of its insulin production. Increased insulin secretion in the baby leads to an efficient metabolism of the excess glucose he receives. Also, this excess metabolized glucose leads to rapid weight gain in the child. The child will be heavier than usual for the gestational age at birth.

Sometimes the weight of the child at birth can exceed 4 Kg. The medical term for this child is macrosome. Abrupt cessation of glucose availability at birth is associated with neonatal hypoglycemia. This low blood glucose occurs on the background of a relative excess insulin produced by the child.

The child’s risks during a pregnancy with gestational diabetes

A baby with blue eyes and a toy in his mouth

Gestational diabetes is associated with several risks for both the fetus and the mother. Short-term complications can occur during pregnancy, at birth or immediately after birth. Besides, gestational diabetes significantly increases the long-term risk for many conditions in both mother and child. Hyperglycemia in the first trimester may go completely unnoticed. Detecting it starting with the 2nd trimester of pregnancy will diagnose gestational diabetes.

The excess weight before pregnancy and the mother’s weekly rate of weight gain significantly amplify the risk posed by gestational diabetes. In the long run, the child will be at increased risk for obesity and diabetes for the rest of his life.

Hyperglycemia in the 1st trimester of pregnancy

Hyperglycemia in the first trimester may increase the risk of miscarriage, early delay in development and congenital disabilities.

Hyperglycemia in the 2nd trimester of pregnancy

If hyperglycemia occurs in the second trimester of pregnancy, the child may later have discrete behavioural disorders or a slight decrease in cognitive abilities. However, they are usually very challenging to notice.

Hyperglycemia in the 3rd trimester of pregnancy

In the last trimester of pregnancy, hyperglycemia can cause more weight gain than expected. The birth of a macrosome (giant) baby is generally more difficult. For this reason, shoulder problems can occur in the case of a natural birth. Delivery can be earlier than expected. Also, hyperglycemia increases the risk of an unscheduled cesarean section delivery.

Immediately after birth, the baby may have difficulty breathing and low blood sugar. Hypoglycemia can occur at any time in the first hours of life. Therefore, doctors will closely monitor the child in this regard. Reasonable control of the mother’s blood sugar before and during labour can reduce the risk of hypoglycaemia in the newborn.

The risks of women with gestational diabetes

A woman jumps over a canyon

Gestational diabetes significantly increases the mother’s risk for all possible complications of pregnancy. Gestational diabetes itself does not increase the long-term risk of diabetes and cardiovascular disease. They may have appeared anyway. However, gestational diabetes is an alarm signal that these diseases are very likely to occur in the future.

The following conditions, in particular, add a high risk of developing gestational diabetes:

  1. During pregnancy
    • Pregnancy hypertension (preeclampsia)
    • Premature birth
    • Caesarean section
  2. After birth
    • Diabetes
    • Cardiovascular diseases
    • Metabolic syndrome

Preventive measures for diabetes and cardiovascular disease are also useful in women with a history of gestational diabetes. They must be implemented as soon as possible and re-evaluated periodically.

The risk of (pre) diabetes in the long run

There is an increased long term risk for any diabetes. However, most women with gestational diabetes will have perfectly normal blood sugar levels after giving birth. Indeed, testing to assess the persistence of a defect in carbohydrate metabolism in the first three months after birth will generally show that everything returned to normal. Still, up to half of women who had gestational diabetes will have gestational diabetes again in a future pregnancy.

The history of gestational diabetes confers a significantly increased risk for the future onset of prediabetes. Also, up to a quarter of women with gestational diabetes will develop type 2 diabetes in the first five years after birth.

The risk for diabetes remains five times higher than expected for the rest of your life. Persistent postpartum obesity leads, in this case, to a 50% risk of long-term diabetes. In contrast, breastfeeding reduces the risk of long-term diabetes significantly.

The history of gestational diabetes also increases the type 1 diabetes risk. This additional risk manifests primarily in women who had gestational diabetes not associated with excess weight. To more accurately determine the risk of type 1 diabetes, it is necessary to dose antibodies specific for type 1 diabetes.

Monitoring of women with gestational diabetes

A round monitoring camera on a white wall.

Monitoring women with gestational diabetes is a hotly debated topic in the online environment. Reliable medical sources in the online environment are generally limited. A starting point may be gestational diabetes presented by the American Diabetes Society. But you will always get the most secure and personalized information from your doctor!

The diagnosis of gestational diabetes involves carefully monitoring the following parameters throughout the rest of the pregnancy:

  • glucose
  • weight gain
  • blood pressure
  • urinary excretion of albumin
  • urinary ketone bodies
  • fetal movements

Blood glucose monitoring in gestational diabetes

All women diagnosed with gestational diabetes should monitor their blood glucose using a glucometer. Blood glucose targets in pregnancy with gestational diabetes are as follows:

  • pre-meal blood glucose ≤95 mg/dl (5.3 mmol/l)
  • blood glucose one hour after a meal ≤140 mg/dl (7.8 mmol/l)
  • blood glucose two hours after a meal ≤120 mg/dl (6.7 mmol/l)

In the first seven days after diagnosis, it would be best if you performed four blood glucose tests a day. An example of their division through a day would be the following:

  1. In the morning on an empty stomach
  2. One hour after breakfast
  3. Before lunch
  4. Two hours after lunch

After this first week, you may reduce the number of daily glycemic determinations, but never to less than one per day.

Frequency of blood glucose determinations

If at any time during pregnancy, all blood glucose levels are below the target for seven days, you may continue with only one glucose test per day. It would be best if you performed it by rotation, before meals, one hour and two hours after meals. However, you should check fasting blood glucose every five days.

When one of the blood glucose tests is higher than the target, the number of blood glucose tests taken daily should be at least two for the following week. You may use any combination of preprandial, one or two hours after a meal blood glucose.

Detection of a total of three blood glucose determinations over the target during seven days requires an increase in the number of measurements to three per day. Besides, it would help if you stepped up the efforts to improve diet and exercise.

The presence of four glycemia above the target after more than two weeks of intensified lifestyle intervention requires diabetic consultation to initiate insulin therapy.

Weight gain in pregnancy

It would help if you weekly monitored the weight gain during pregnancy, in the presence of gestational diabetes. Women who manage to maintain a standard rate of weight gain in the 2nd and 3rd trimesters will have a significantly lower risk of having an overweight child at birth.

Women with an average weight before pregnancy should have a total weight gain of up to 16 Kg at birth. Their weight gain rate in the 2nd and 3rd trimesters should be a maximum of 0.4 Kg per week. If there is a small excess weight before pregnancy, the increase will be a maximum of 0.3 kg per week, with a maximum of 11 Kg gained at birth. Obesity at the time of conception reduces these figures to 0.2 Kg gain per week, with a maximum of 9 Kg extra weight at birth.

Urinary excretion of albumin

It would be best if you monitored the blood pressure and urinary albumin excretion weekly. A simple urine test performed at home can detect the occurrence of proteinuria (protein in the urine).

This urine test consists of strips that are coloured differently for different substances. In the absence of hypertension or other risk factors, one determination per month at home is sufficient.

Monitoring urinary ketone bodies

Diabetic ketoacidosis is entirely exceptional in a woman with gestational diabetes in the absence of a severe precipitating factor (e.g. a significant infection). Therefore, monitoring of urinary ketone bodies does not aim to detect diabetic ketoacidosis in time.

The purpose of evaluating ketone bodies in the urine of women with gestational diabetes is to assess the sufficient intake of carbohydrates in the diet. Their deficiency can lead to increased urinary ketone bodies. Urine summary strips are coloured differently depending on the concentration of ketone bodies in the urine. This monitoring is entirely optional. If you decide to do it, it is generally enough to check it once a month, as in the case of urinary albumin excretion.

Monitoring of fetal movements

The woman with gestational diabetes should carefully monitor fetal movements in the last ten weeks of pregnancy. It would be best if you informed your obstetrician of any changes from usual.

Treatment of gestational diabetes

Lots of vegetables.

The general principles of care during pregnancy in women with diabetes known before pregnancy also apply in gestational diabetes. The first therapeutic step is lifestyle changes. Healthy lifestyle means more than healthy eating. If this intervention is not enough, we will move on to the next stage, the pharmacological intervention.

Lifestyle intervention addresses the following issues:

  • diet
  • physical exertion
  • adapting to stress
  • observance of sleep hours

Improving lifestyle increases the chance of avoiding postnatal depression and also to eliminate the excess weight after birth. Lifestyle changes may be sufficient if the following initial conditions are met:

  1. Fasting blood glucose is below 126 mg/dl (7 mmol/l)
  2. Two-hour blood glucose in the glucose tolerance test is below 200 mg/dl (11.1 mmol/l)

Diet in gestational diabetes

The diet during pregnancy should contain 175 g of carbohydrates (carbohydrates) per day. It is not a good idea to use the hypoglycemic diet, with 60-90 g of carbohydrates, as in type 1 diabetes. More so, the ketogenic diet, with less than 30 g of carbohydrates per day is dangerous.

An increase in lipid intake often accompanies restriction below 150 g of carbohydrates per day. This excess of fat, even if it is of good quality, will significantly increase the risk of child overweight at birth.

Besides, the lipids in the mother’s diet increase the resistance to insulin during this period. You may divide the recommended 175 g of carbohydrates into three main meals and 2-4 snacks. To better calculate the amount of carbohydrates (carbohydrates) in the diet, you need to consult the nutrition tables.

The number of calories in pregnancy with gestational diabetes

The number of calories per day generally varies between 1800 and 2500 Cal. It would help if you adjusted calorie requirements continuously based on the recommended weekly weight gain. In the first trimester of pregnancy, the recommended number of calories is the same as for a nonpregnant woman. The 2nd trimester of pregnancy involves the addition of 340 Cal/day. For the 3rd quarter, you may add 452 Cal/day.

Food choices in pregnancy with gestational diabetes

It would be best if you consumed over 50% of carbohydrate from vegetables. Eat them as fresh as possible, in salads. Around 3-4 fruits per day will help you gain the needed vitamins. However, you may want to eat them before 5 pm. Avoid eating too sweet fruits, such as plums, bananas or grapes. Also, try to reduce the amount of potatoes and flour products (bread, pasta).

At bedtime, it helps to eat a small protein-rich supplement. If there is increased urinary excretion of albumin, you may want to reduce the proteins intake to 1 g/kg-body-weight/day.

Saccharin is contraindicated in pregnancy because it crosses the placenta and can reach the fetal circulation. Aspartame and sucralose are safe non-caloric sweeteners.

Physical exertion in gestational diabetes

It would be best if you adapted the physical effort to the conditions of pregnancy. Light-medium aerobic exercise should cover at least 150 minutes a week. Use a minimum of 30 minutes per day for this activity, at least five days a week. It is not acceptable to spend more than a day without any physical activity training.

Anaerobic physical effort (e.g. weight lifting) is allowed, but with great care and strictly within the limits of individual comfort. You may do physical exertion using only the upper limbs, including lifting light weights (0.5 Kg).

Insulin treatment in gestational diabetes

If you cannot achieve the glycemic targets through diet and exercise, you may require pharmacological treatment. Metformin and glibenclamide are oral antidiabetics formally contraindicated in pregnancy. Their use in the 2nd and 3rd trimesters of pregnancy is outside the official recommendations. However, pregnant women who used them did not experience significantly increased risks. Still, we cannot recommend their use in pregnancy.

The only approved pharmacological way to lower your blood sugar during pregnancy is insulin. Your doctor will recommend insulin treatment if at least one-third of the total blood glucose determinations within a week exceed the established threshold (see above). Also, you may start insulin therapy if at least four blood glucose measurements exceeded the expected values within seven days.

Often, you can use a 24h insulin taken as a single dose per day. Its administration stops after birth in most cases. A slow-acting insulin analogue is generally used in the evening or the morning, depending on the context.

A sudden drop in insulin requirements in a woman with gestational diabetes means that there is a significant problem with the placenta or the baby. Usually, insulin therapy stops abruptly immediately after birth. You may need to restart it if carefully monitored blood glucose levels require it.

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