Author’s note: We reflect on the life-long work of Dr. Lois Jovanovic, who pioneered the standards of care for pregnant women with diabetes.

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As you prepare for pregnancy with diabetes, the stringent blood glucose control targets may seem daunting. This article will review the recommended blood sugar levels for pregnancy, discuss the medications used to treat diabetes in pregnancy and provide key tips to achieving normal blood glucose levels as frequently as possible.

Let’s begin by reviewing the recommended blood glucose targets during pregnancy.

Blood Glucose Targets

Most professional health organizations that issue guidelines on blood glucose levels during pregnancy, including the American Diabetes Association (ADA) and the American College of Obstetricians and Gynecologists (ACOG), agree that achieving normal blood glucose levels as much as possible before and during pregnancy facilitates the best outcomes.

For example, the ADA recommends:

Fasting blood glucose level of <95 mg/dL (5.3 mmol/L)

One-hour postprandial blood glucose level of <140 mg/dL (7.8 mmol/L) OR two-hour postprandial blood glucose level of <120 mg/dL (6.7 mmol/L)

An A1c of less than 6%

Of course, these targets may be individualized slightly. For example, if a woman is unable to safely achieve these recommendations, without experiencing significant hypoglycemia, the healthcare team may agree that relaxing the targets slightly may be reasonable.

By contrast, some women may feel that they can achieve even more stringent targets. Truly normal blood glucose levels during pregnancy rarely exceed 120 mg/dL. For example, a study that used continuous glucose monitoring of non-diabetic pregnant women demonstrated the tight physiological regulation of blood glucose in the early and late stages of pregnancy.

If more stringent blood glucose control can be achieved safely, there is a good reason to strive for it. “Tighter control, if achieved safely, has better outcomes,” researchers summarize.

Of course, for most women with diabetes, it is not realistic to expect to be in range 100% of the time. However, the closest one can get to that without experiencing severe hypoglycemia is the goal. In general, if a woman is meeting the recommended targets the majority of the time, and achieves an A1c level of less than 6%, this is considered very good control, and greatly reduces the probability of adverse outcomes.

Blood Glucose-Lowering Medications

While all women with type 1 diabetes use insulin, some women with type 2 diabetes may be diet-controlled or use oral medications to manage blood glucose levels. Some women with type 1 diabetes may also use an oral agent, such as metformin. So, which insulins are considered safe to use in pregnancy, and what about oral blood glucose-lowering medications?

Insulin is the preferred treatment to manage blood glucose levels during pregnancy with diabetes for several reasons. Insulin formulations do not appear to cross the placenta, while oral medications do cross the placenta, and there is a lack of long-term studies and safety evidence for any of the oral drugs.

Also, some data suggest that “metformin may slightly increase the risk of prematurity,” while “glyburide was associated with a higher rate of neonatal hypoglycemia and macrosomia than insulin or metformin in a 2015 systematic review.” Finally, researchers note that for many women with type 2 diabetes, oral agents may be insufficient to maintain optimal glycemic control.

Of course, there may be exceptions to the general recommendations. If the healthcare practitioner or team determine that the benefits of using an oral medication during pregnancy outweigh the risks, the patient may be treated with oral agents, alone or in combination with insulin.

When it comes to insulin therapy, researchers explain that although “most insulins carry an FDA Pregnancy Category…in 2015, the FDA ruled that the lettering system will no longer be used” and that “a risk assessment must be done on an individual patient basis.”

Thus, women should discuss their insulin use with their healthcare team to determine whether any treatment adjustments need to be made before becoming pregnant. It is likely that many physicians would strive to provide patients with the best tools to maintain optimal glycemic control. Although there is a lack of human safety data for some insulin preparations, the potentially serious consequences of hyperglycemia are well-established. Today, many women continue to administer analog insulin(s) during pregnancy.

Managing Your Blood Glucose Levels

Here are some strategies to help you maintain normal blood glucose levels as consistently as possible:

Optimize Basal Insulin Dosing

Basal (long-acting) insulin is the background insulin that regulates blood glucose levels in the absence of meals. This means that the basal insulin dose should be tailored to match the liver’s glucose output around the clock. Ideally, if the basal insulin dose is set correctly, blood glucose levels should not fluctuate in the absence of food.

To determine if the basal insulin dose is set correctly, one can fast for a specific number of hours without bolus (fast-acting) insulin onboard and monitor blood glucose levels to see if they remain steady. Importantly, the test should be performed in the absence of other complicating variables, like exercise, stress, or illness. The test should not be performed if your blood glucose level is low or high.

Many people prefer to perform basal testing in 8-12-hour spurts, so as not to fast for an entire 24 hours. For example, it can be quite easy to check the overnight basal dose by not eating after 6 pm and assessing the blood glucose trend from 10 pm to 6 am (in the absence of food or bolus insulin). To determine the basal dose efficacy for morning or evening hours, one would skip a meal and monitor blood glucose levels to determine whether the basal dose is well-set.

The basal insulin requirement may be very similar throughout the day, or it may vary. In particular, many individuals experience “dawn phenomenon,” whereby hormones stimulate glucose release by the liver in the early morning hours. When using an insulin pump, it is quite easy to adjust the basal insulin rate of delivery to accommodate any variations. For those on insulin injection therapy, it may be worthwhile to split the basal insulin injections into several doses throughout the day, to best match the requirements. These individuals may also benefit from taking a small amount of short-acting insulin upon waking to account for dawn phenomenon.

Accurate basal insulin dosing is the first step to achieve the best blood glucose control possible. Once the optimal doses or rates are determined, one should not need to worry about hyper- or hypoglycemia in the absence of food or other variables (like exercise). This will make it a lot easier to systematically start addressing other variables that affect blood glucose levels.

Optimize Bolus Insulin Dosing

After optimizing the basal insulin dose, the next logical step is to work out how to best administer bolus (fast-acting) insulin to cover meals and snacks. A few factors are at play here: accurate carbohydrate counting, the glycemic index of the meal, the protein content of the meal, as well as the timing of the insulin dose. Much like with basal insulin, bolus insulin needs may also vary depending on the time of day.

Carbohydrates will affect blood glucose levels the most. This is why it is especially important to learn how to count carbohydrates and to have an accurate insulin-to-carb ratio. It is critical to count everything; for example, two cups of spinach or eight olives still contain approximately 2g of digestible carbohydrate. For many individuals with diabetes, there is no such thing as a “free food.”

It can be very difficult to accurately determine the carbohydrate content, especially when one is consuming a large amount of carbohydrate. Food labels are allowed a 20% margin of error, and many produce items, like fruit and starchy vegetables, can be quite variable in their carbohydrate content, even when one diligently weighs the food and performs the appropriate calculation. Restaurant food and hidden carbohydrates (e.g., in sauces) can also wreak havoc on the calculation accuracy.

Furthermore, insulin dosing isn’t a perfect science; variability in absorption and activity profile are considerable. This is why lowering the total carbohydrate count and obtaining the majority of nutrients through quality protein sources and an abundance of non-starchy vegetables, as well as preparing most meals yourself, can go a long way to minimizing insulin dosing errors.

Also, many people find that they have to account for the protein content of the meal with insulin. You can read more about calculating insulin doses for protein here.

Trial and error will help you to determine your optimal insulin-to-carb ratio, if and how much insulin you require for protein, as well as the optimal bolus timing for different kinds of meals. For example, a carbohydrate-rich meal is much more likely to require a substantial pre-bolus than one that is low-carb. Also, you may find that high-fat meals can delay the food absorption and require less of a pre-bolus.

Finally, once you figure out what works best to keep your blood glucose levels steady and in the normal range, keeping meals as consistent as possible can go a long way to helping you achieve the desired results time and time again. Finding meals that are nutritious, enjoyable, and easy to bolus for, is key to optimizing glycemic management while feeling satisfied with your diet.

Get Back in Range with Precise Corrections

Generally, the more your blood glucose is in range, the easier it is to keep it there. Insulin may not have the same effects when blood glucose is high or low, so it is important to try to get back in range as quickly as possible.

If your blood glucose is high, try to wait to eat until your blood glucose is in range. Administering an insulin correction, alongside food and a bolus dose, will make it more difficult to normalize your blood glucose level and may result in prolonged hyperglycemia.

Treat hypoglycemia with a very precise amount of glucose. Figure out how many grams of glucose is required under different circumstances to get back to the normal range. This will take trial and error and will vary depending on the insulin-on-board, the blood glucose value, and other parameters (like whether the blood glucose level is steady or dropping).

Very precise corrections with insulin or glucose, while keeping other variables out of the equation until you are back in range, is key to minimizing the likelihood of a blood glucose “roller coaster.”

Maintain a Consistent Routine

So many variables can affect insulin activity and blood glucose levels. If one can keep as many of these factors as possible consistent from day to day, this can go a long way in making it easier to manage blood sugar levels.

The main variables include stress levels, sleep time and quality, exercise, and food choices. Trying to minimize stress, getting enough sleep, eating nutrient-dense foods, and maintaining a consistent exercise routine can help to improve insulin sensitivity.

Having a solid routine that reduces the variability in these parameters can minimize the frustration of troubleshooting when blood glucose levels are out of range.

Make Use of Technology

Using a continuous glucose monitor (CGM) can be very valuable for any person with diabetes, and is an especially useful tool for those striving to maintain very tight glycemic control. The CGM can provide the most comprehensive picture of blood glucose trends, day and night. The ability to program high and low blood glucose alarms can also help minimize out-of-range values, and provides an additional safety net against hypoglycemia, especially at night. A recent study concluded that “the use of continuous glucose monitoring in women with Type 1 diabetes in pregnancy is associated with improved glycaemic control and neonatal outcomes.”

Many people find that using an insulin pump can help to optimize basal and bolus dosing. Having the ability to deliver basal and bolus insulin in very precise amounts, as well as temporarily alter or suspend insulin delivery can be very useful. Also, integrated pump and sensor technology is quickly becoming more popular and can help many individuals improve their blood glucose control. Research is ongoing to determine whether closed-loop insulin delivery can improve pregnancy outcomes for women with diabetes.

It is worthwhile to consider utilizing the available technology to help you reach your goals. In particular, having a CGM can go a long way in optimizing management. Of course, it is not an option for many people (e.g., due to financial constraints). In this case, it is particularly important to check your blood glucose levels frequently. The more data that is available, the more knowledge you will have to make the most relevant treatment decisions and adjustments.

Make Frequent Adjustments

Diabetes management is never set-it-and-forget-it. Instead, it is a dynamic and complex process. Metabolism is a very complicated system—no wonder it can feel very frustrating at times to try to keep up with successfully managing the condition.

Frequent blood glucose monitoring (via finger stick or CGM) is the most important factor in being able to quickly spot any trends that require insulin dosing adjustments. Many factors can necessitate treatment changes, including weight loss, medications, illness, and hormonal changes, to name a few.

If you do not feel comfortable managing your own insulin dosing adjustments, it is critical to work with an experienced health care practitioner or team (e.g., endocrinologist, educator, etc.) to determine the most appropriate strategies and to help you make changes whenever needed. However, diabetes is a condition where self-management is key; learning what works for you and gaining confidence in making your own treatment decisions can be paramount. Making a science experiment of it can help you gain confidence and achieve the best results.

Conclusions

Trying to maintain normal blood glucose levels around the clock can be a very daunting task. Approaching all the variables systematically to arrive at the most accurate insulin dosing strategies and staying consistent once you figure out what works best is key to achieving the glycemic goals as much as possible.

Do not be discouraged if it takes some time to get to where you want to be. It is not an easy task, but with the right tools and strategies, excellent blood glucose control is achievable and well worth it to maximize the odds of having a healthy pregnancy!

References

American Diabetes Association; “Management of Diabetes in Pregnancy: Standards of Medical Care in Diabetes—2018” (2018) Diabetes Care 41(S1): S137-143. http://care.diabetesjournals.org/content/41/Supplement_1/S137

Blum AK; “Insulin Use in Pregnancy: An Update” (2016) Diabetes Spectrum 29(2): 92-97. http://spectrum.diabetesjournals.org/content/29/2/92

Feig DS and Murphy HR; “Continuous glucose monitoring in pregnant women with Type 1 diabetes: benefits for mothers, using pumps or pens, and their babies” (2018) Diabetic Medicine 35(4): 430-435. https://onlinelibrary.wiley.com/doi/epdf/10.1111/dme.13585

Harmon KA, Gerard L, Jensen DR, Kealey EH, Hernandez TL, Reece MS, Barbour LA, Bessesen DH; “Continuous Glucose Profiles in Obese and Normal-Weight Pregnant Women on a Controlled Diet” (2011) Diabetes Care 1-7. http://care.diabetesjournals.org/content/diacare/early/2011/07/13/dc11-0723.full.pdf

Stewart ZA, Wilinska ME, Hartnell S, O’Neil LK, Rayman G, Scott EM, Barnard K, Farrington C, Hovorka R, Murphy H; “Day-and-Night Closed-Loop Insulin Delivery in a Broad Population of Women With Type 1 Diabetes: A Randomized Controlled Crossover Trial” (2018) Diabetes Care dc172534. http://care.diabetesjournals.org/content/early/2018/03/12/dc17-2534

Read more about A1c, American Diabetes Association (ADA), blood glucose monitoring, continuous glucose monitor (CGM), diabetes management, insulin, pregnancy, type 1 diabetes, type 2 diabetes.