Gestational Diabetes: Testing For Ketones

by KMom

Copyright 1998 KMom@Vireday.Com. All rights reserved.

DISCLAIMER: The information on this website is not intended and should not be construed as medical advice. Consult your health provider. This particular web section is designed to present more than one view of a controversial subject, pro and con. It should be re-emphasized that nothing herein should be considered medical advice.



What are Ketones?

Ketones are formed when your body's fat stores have to be accessed for energy. Normally, you eat food and then the body converts it to glucose/blood sugar for use as energy by your cells. Your insulin is then like a key, unlocking the door to the cell so it can access this blood sugar. In pregnancy, placental hormones make you more resistant to your own insulin (in essence 'warping' the key to the door) and make it harder to get that glucose from your blood into your cells. So while your blood remains high in blood sugar, your cells can be starving. The fetus absolutely must have energy, so if your pancreas cannot make enough insulin to overcome the hormone-caused resistance, the cells start accessing other sources of energy, like fat stores. The by-product of this is ketones.

Ketones may be dangerous when pregnant, although this is controversial and still being studied and disputed. There were several studies that showed that babies exposed to a lot of ketones had learning problems and reduced IQ later in life. These have since been disputed by other studies, but just in case, everyone plays it safe during pregnancy, which is very prudent.


What Causes Ketones?

Ketones usually occur because you are either:

  1. not eating enough total calories
  2. going too long between meals
  3. skipping meals/snacks
  4. nauseous, not eating well/throwing up, and so not getting enough food for energy
  5. so insulin-resistant from hormones that your body cannot access the blood sugar that's there

Your doctor or midwife should have you monitoring your first morning urine for ketones daily. Because of the long overnight fast, blood sugar can drop too low in the night, and the body would have to turn to other sources of energy like the fat stores, thus giving off or 'spilling' ketones. Since this is potentially dangerous for the fetus, it is important to detect whether this is happening. Your morning blood glucose numbers on your glucometer would not reflect ketones, nor would your bG numbers necessarily be low, since energy had been obtained from other sources. It is possible for your bG numbers to be normal or even high and yet to also be spilling ketones. This is why testing for ketones is also an important part of gd care. You cannot assume that because your bG numbers are ok that you are not spilling ketones.

The Ketone Controversy

Not all providers who deal with gd even monitor ketones or place much emphasis on them. Some are not convinced that ketones pose a potential health threat to the fetus. And yet, some providers place great emphasis on ketones, while still others try to avoid them but do not give much attention to the issue one way or the other. It's hard to know how important the issue really is.

In the past, several studies have shown lower IQ and higher rates of learning problems in the children of diabetic pregnancies that had a lot of ketonuria (ketones 'spilled' in the urine). Yet other studies that reviewed the first studies either were not able to confirm the first data or attributed them to some other cause, such as amniotic infections at birth, etc. Knopp et al., reviewing the issue and the evidence in the Journal of the American College of Nutrition ("Hypocaloric Diets and Ketogenesis in the Management of Obese Gestational Diabetic Women", 1991) write that:

"Even if the ketonuria in GDM were associated with lower IQ in offspring, it seems more likely that the overall poorer diabetic control resulting in ketonemia is more responsible for the lower IQ than an effect of ketone bodies per se...In any case, there is no consistent epidemiologic link between maternal ketonuria per se and impaired fetal growth and development."

It should be pointed out that his reasoning does not exonerate ketones from blame, just casts doubts---still an important point. On the other hand, most major authorities remain concerned about the influence of ketone levels and advocate avoiding them. The diabetic food plans are designed with frequent small meals spaced carefully throughout the day in an effort to keep blood glucose (bG) even and to prevent ketones from developing, just in case they are harmful after all. The American Dietetic Association's journal, in its 1995 article reviewing nutrition management in women with gd, notes that:

"Two studies have indicated that ketonemia and acetonuria in the pregnant woman are associated with lower IQ in the offspring. These studies do not provide definitive data and more research is needed, but it appears prudent to avoid ketosis in pregnancy. The current recommendation is daily or periodic testing of the first voided specimen of urine for ketones. Dietary adjustments may be needed if trace of greater amounts of ketones present."

The issue of ketones is particularly pertinent to large women since ketones can be brought on by the use of low-calorie food plans, often prescribed to obese gestational diabetics and even obese pregnant women without gd (see the debate on this issue in the section on GD: Nutrition Questions). This common practice of giving hypocaloric diets without extremely careful attention to ketone testing should be questioned, and the even the practice of giving obese women just enough calories to keep them just above the level of ketonuria should be questioned, since very little has been done to establish the long-term safety of near-ketonuria levels. This is an area greatly neglected in the research on hypocaloric diets for obese pregnant women. Although hypocaloric plans offer apparent benefits in some cases, the safety of this approach has not been established adequately, and a number of sources urge caution in their use.

For example, the American College of Obstetricians and Gynecologists (ACOG) says that "while maternal weight gain and fetal macrosomia may be decreased, the safety of this approach has not been established, and thus it is not recommended" (ACOG Bulletin #200, 1994). A number of other sources also recommend caution in approaching hypocaloric diets for obese women, including Gunderson in her 1997 article in Diabetes Care ("caloric restriction during pregnancy even in obese women must be viewed with caution, since its effects may pose some risk to the fetus") and Hachey in his 1994 article in American Journal of Clinical Nutrition ("more caution is necessary in using fat- and energy-modified diets to treat women with gestational diabetes mellitus"). In addition, the 1995 Journal of the American Dietetic Association article quoted above also notes that "Risk of high levels of blood ketones and risk of sacrificing maternal nutritional status are higher in women who consume hypocaloric diets." Far more attention to this in the research is necessary and has largely been ignored thus far, so hypocaloric diets for obese gestational diabetics must be treated with great caution and reserve.

Ketones can also be present even when caloric intake is adequate, especially if intake is sporadic or there are large gaps in time between meals. Large swings in blood sugar may also exacerbate the ketone problem, and newly diagnosed gestational diabetics often find that they have some levels of ketones present. As long as these ketones are mild and are tested for and resolved, they are probably not a huge health drain unless large levels are present and are unable to be resolved. Some studies have found that many normoglycemic pregnant women experience some levels of ketonuria at some points in pregnancy, though probably not as strong as in women with gd. Kmom is not a medical expert on ketones, but her reading indicates that the consensus seems to be that small amounts on occasion are probably not a serious problem but should be avoided if possible; larger amounts or consistent amounts are more of a worry. Just how much and how often constitute a concern is a matter of debate.

In summary, although ketones have not been conclusively proven to be dangerous, neither have they proven to be benign, and there is a fair amount of data linking significant amounts to problems in the baby. It seems safest at this time to err on the side of safety and carefully test for and avoid ketones. It is Kmom's opinion that any provider who does not place a high priority on this should be questioned strongly.


Ketone Tests vs. Other Urine Tests

It is important not to confuse ketone urine testing for the old urine blood sugar tests. These are different tests. In the old days before the current set of blood sugar tests, women were tested for 'gd' by using urine sugar tests. Only if a woman was spilling significant amounts of sugar in her urine was she tested further to see if diabetes was a problem. These tests were not sensitive enough to detect most cases of what we call gd today, so if your mother was 'tested' for gd in the old days by this method, you cannot definitely say that she did not have it back then.

To make the subject of urine testing even more complicated, diabetics used to be able to test their blood sugar levels only through the use of color-coded strips they dipped in their urine. Exact readings were impossible; the color coding only told diabetics in what range their bG was. A certain color told them they were low, another told them they were just right, another told them they were a little high, another that they were even higher, etc. Nowadays, the advent of self blood-glucose monitors (SBGM) has revolutionized blood sugar control. Now, instead of only getting a vague picture of what their blood sugar is doing, diabetics can get pinpoint accuracy, making tighter control far more possible and thus helping to reduce side effects greatly. In particular, SBGMs have helped pregnant diabetics greatly improve their pregnancy outcomes, since bG control during pregnancy is so much tighter than when not pregnant. SBGMs have been nothing short of a miracle for diabetics and gestational diabetics. Studies show improved outcome with their consistent use by patients at home.

In spite of this, your urine is still tested for sugar with the old strips at each prenatal visit to be sure you are not spilling a lot of sugar, which could indicate the need for more sensitive blood glucose screenings or new treatment. However, it is not unusual for some sugar to be present in urine on various occasions (even in women without gd), or for women with gd not to have excessive sugar in their urine either. So the urine test for sugar, while routine, is not considered definitive for diagnosing gd problems. Your urine is also tested at prenatal appointments for the presence of protein (which could indicate problems with pre-eclampsia) and white blood cells (which could indicated the presence of a bladder infection). These are all various types of urine testing done on pregnant women.

However, ketone testing is different. These other urine tests have NOTHING to do with ketone testing, and it's important to distinguish between them. Some patients and even some providers get confused between tests, especially the old urine sugar tests and the ketone tests. [One of Kmom's doctors did.] A few providers occasionally do not have their patients test for ketones; sometimes this is because they are not convinced that it is important, but sometimes it is because even they are confusing the other urine tests with ketone testing. Ketone testing is considered by most providers to be a vitally important part of monitoring during gd. If your provider does not have you regularly testing your ketones, you may want to question them further about why, or even consider switching to a new provider.

Testing and Managing Ketones

Ketone sticks are available in most pharmacies and no prescription is usually needed. If money is an issue, cut the ketone strips in half, length-wise (you only need a small narrow surface to determine if you are spilling ketones). This will give you twice the strips for the same amount of money. Then, during your first morning urination, you use the ketone stick. The end of the stick will turn colors of varying intensity if your urine has ketones in it, or will remain neutral if no ketones are detected. The amount (or lack) of ketones should be noted in your daily bG diary so you have a long-term record of it.

There are four general levels of ketones: trace, small, moderate, and large. The importance and management of these levels varies somewhat from provider to provider; consult your provider on how to manage your results. The following guidelines are provided for discussion purposes, and are basically the guidelines given Kmom by her diabetes educator in her first pregnancy, which were based on state recommendations in a nationally recognized Diabetes in Pregnancy program. In general, diabetes educators and doctors specializing in diabetes take ketone results much more seriously than OBs, which may reflect a lack of education on the part of OBs, although the debate over the importance of ketones continues. Again, it seems better to err on the conservative side in this issue at this time.

Generally, a trace of ketones on occasion is not considered very serious, though you should discuss it with your provider. Consistently spilling a trace of ketones is of more concern and should be discussed with your provider as soon as practical. Spilling small amounts of ketones should be reported to your provider as soon as possible, and spilling moderate or large amounts of ketones should be reported immediately, as it can be serious. Some providers will have you drink a glass of milk if you are spilling ketones, and if you are regularly spilling ketones in the night, will ask you to add a glass of milk at 3 a.m. or so. For many women (Kmom included), this glass of milk in the night can be enough to solve the ketone problem. However, do not attempt to treat this problem yourself; check with your provider about this problem instead, as there are multiple factors to be considered.

To prevent ketones in general, you should be eating every 3-4 hours in pregnancy, so that your body has a constant supply of energy and never needs to access the fat stores. You should also have a very good bedtime snack, which for most women includes 2 starches, 1 milk, and 1-2 proteins. The protein is extremely important, as it slows the absorption of the carbs and makes their energy available more evenly and over a longer period of time, thus lowering the risk of an early morning bG dip. You should have no more than 9-10 hours between bedtime snack and breakfast (9 is better), so your bG does not drop too low. [Note: Some providers occasionally recommend a 12-hour time between snack and breakfast, but most providers recommend 9-10 hours.]

If you are getting persistent ketones, despite a good bedtime snack and even a glass of milk in the night, you should consider whether you are eating enough calories. Pregnant women of size generally need somewhere around 2200k or so, more or less; more for twins. Some providers have experimented with restricting large women with gd to 1200-1800k daily, in an effort at keeping the babies from growing too large or the mother from needing insulin. Some scholarly journals and leading researchers have advocated very low caloric intakes for large pregnant women with gd, although ACOG does not recommend this, as noted above.

If your provider has you on anything less than 2000k a day, you may not be getting enough. So if you are getting consistent ketones, it may be that you need more calories per day than what you are being given. HOWEVER, you should not gratuitously add calories yourself, but discuss it with your provider instead. A registered dietician can guide you on how to add calories and foods to your diet wisely instead of unwisely, and whether it's necessary. Some women have found anecdotally that adding extra protein at night or at their 'problem' times seems to help keep their bG readings more even, but again, nutritional balances can be complicated and you need to consult an expert.

Another possible source of ketone production could be an abnormally strong insulin reaction to food. In this, the mother gets a very strong, swift rise in bG from eating, causing a big spike in blood sugar. This is followed by an abnormally strong surge in insulin production, causing a precipitous dip in bG later. If you get the shakes or irritable when you don't eat for a while, you may have this abnormal blood sugar spike and then insulin surge. Check your 3-hour GTT results. If your 1-hour number was very high, but you showed a strong and sudden dropoff after the second or third hour, you may have a tendency towards reactive hypoglycemia. This can also cause more ketones. The key to handling hypoglycemia is eating more protein, more frequently, and being sure that you have enough proteins with your carbs. Protein evens out the conversion of carbs to blood sugar and makes for more even, more long-lasting energy supplies. In this way, you can avoid the strong surges and drops characteristic of this problem. However, be sure to consult an expert if you suspect that this may be a problem for you. It can be a difficult problem to manage.

Women who experience severe nausea and so do not eat well or throw up a lot of their food tend to have blood sugar and ketone problems as well. This can be a vicious cycle, since low blood sugar tends to make you even more nauseous. The key to handling this is to force yourself to eat in spite of the nausea, and to emphasize protein foods along with your carbs. It's terrible to have to eat when you are nauseous (Kmom knows!), but you risk making your nausea even more severe by omitting food or fasting for long stretches. Small, frequent meals that include lots of protein are the key to making nausea more easy to handle and to not make it worse. You may not need to eat all your usual food, but eating some (of the right type) is important. Other ideas for handling nausea can be found in a different section of this website. Also consult your registered dietician for specific hints on handling nausea in a diabetic pregnancy.

Although many women newly diagnosed with gd have problems with controlling ketones at first, they are usually able to get them under control within a few weeks, many in even less time. Occasional traces of ketones does not seem to be a very serious problem, but larger amounts or frequent bouts with ketonuria may be a bigger problem and probably indicates a problem with blood glucose control that needs to be solved. Although the controversy over the long-term effects of ketonuria is still being debated, in Kmom's opinion it seems most sensible to err on the conservative side in this issue and be very careful about avoiding ketones as much as possible.


Kmom's Ketone Story

Kmom's Story: In my first pregnancy, I was extremely nauseous. The doctor told me not to worry about eating if I didn't feel well, which probably made my blood sugar swings even more extreme. I would go from periods of extreme nausea to sudden periods of total starvation, with very strong cravings for protein foods. In hindsight, this was probably the gd beginning to become a problem, though I had tested negative for it in the first trimester. The advice from my doctor to not worry about eating if I was nauseous probably exacerbated the problem, and probably made the low and high swings in bG even more pronounced. This and the tremendous life stress happening at this time probably brought out an underlying genetic tendency towards diabetes and caused it to express itself during that pregnancy. And of course, I was an older mom and heavyset, both of which are also risk factors.

The nausea lasted for about seven looooooong months, and actually disappeared only about the time I was discovered to have gd and placed on a diabetic food plan to even out my bG. Once I started eating on the diabetic food plan and concentrated on the timing, frequency, and combinations of foods, the nausea really started to ease off, which could of course also be a coincidence. It's hard to say with certainty that these two events are connected, but it's suspicious!

At first when I was diagnosed in that pregnancy, I had a lot of trouble with ketones. This is very common in the beginning. My OB was very cavalier (and possibly ignorant) about it and probably would not have had me check them at all, but my diabetes educator was definitely concerned, so I paid attention to them. Part of the problem was probably that my body needed time to recover from all the uneven swings of the nauseous first 7 months, and part of the problem was that sometimes I omitted my bedtime snack protein, not understanding how important it was. My ketones continued until my diabetes educator suggested adding a milk in the middle of the night. This seemed to even things out more, and I had no more troubles with ketones.

In my second pregnancy, I followed a gd food plan from before conception. I did experience nausea, but forced myself to eat anyhow (at least some), emphasizing the proteins. I also understood the role of protein in the bedtime snack better and was careful to follow those guidelines exactly. This time the nausea was less severe and lasted only 3 months. At no time in the second pregnancy did I experience ketones, nor did I need to add the milk in the middle of the night. So now I'm a firm believer in the power of prevention and proactive eating!


Ketone References

Fagen, C. et al. Nutrition Management in Women with Gestational Diabetes Mellitus: A Review by ADA's Diabetes Care and Education Dietetic Practice Group. Journal of the American Dietetic Association. 95(4):460-7. April 1995.

An overall view of some of the controversies and issues in gd nutritional guidelines. Notes strong concern for "high levels of blood ketones and risk of sacrificing maternal nutritional status [among]...women who consume hypocaloric diets." Notes that "it appears prudent to avoid ketosis in pregnancy." Extensive list of related references.

Hachey, David L. Benefits and Risks of Modifying Maternal Fat Intake in Pregnancy and Lactation. American Journal of Clinical Nutrition. 59(suppl):454S-64S, 1994.

A review of the risks of the normal rise in cholesterol and triglycerides in pregnancy (women with multiple pregnancies often experience increased angina and gallstones due to the hypercholesterolemia of pregnancy) and whether a low-fat or modified diet can help lower those risks in pregnant, lactating, and/or gd women. Technical but interesting. "More caution is needed in using fat- and energy-modified diets to treat women with gestational diabetes mellitus (GDM)."

Gunderson, Erica P. Intensive Nutrition Therapy for Gestational Diabetes: Rationale and Current Issues. Diabetes Care. 20(2):221-26, February 1997.

Excellent article reviewing controversies in nutrition recommendations and therapies, using insulin vs. diet-control only, etc. Points out that current research designs have mostly concentrated on examining caloric restriction's effectiveness, ignoring related issues such as frequency of meals/snacks, restriction of carbohydrate as percentage of total calories, and distribution of carbohydrate throughout the day, an excellent point. A closer look at the finer points of dietary management may prove effective in reducing the number of women needing insulin, and should be evaluated along with other alternative therapies such as exercise therapy. Says that "caloric restriction during pregnancy even in obese women must be viewed with caution, since its effects may pose some risk to the fetus." An excellent article to review the fine points of nutrition issues, though a bit technical for the beginner.

Knopp, R.H., et al. Hypocaloric Diets and Ketogenesis in the Management of Obese Gestational Diabetic Women. Journal of the American College of Nutrition. 10(6):649-67. 1991.

Ran two studies on hypocaloric diets. One severely restricted caloric intake by 50% (to 1200 calories); this improved glycemic control but strongly raised levels of ketones. The second trial used a moderately restricted (33%) diet (about 1600-1800 calories) which improved bG levels without raising ketone levels as much, and improved control better than prophylactic insulin. Studies were very short-term, lasting only a week or two, and needs further study. Of special import to this section, this article discusses the controversy over whether ketones adversely affect the fetus. Notes design problems with previous research on the subject. Contends that ketonuria "is of uncertain significance".

Magee, M.S., et al. Metabolic Effects of a 1200 Calorie Diet in Obese Pregnant Women with Gestational Diabetes. Diabetes. 39:234-240. 1990.

Found strong amounts of ketones after 1200k diet was used; discontinued the study after a short period due to safety concerns.

Churchill, J.A., et al. Neuropsychological Deficits in Children of Diabetic Mothers. American Journal of Obstetrics and Gynecology. 105:257-268. 1969.

One of the first big studies to really pinpoint a possible link between ketone by-products in pregnancy and problems in the offspring later.

Rizzo, T. et al. Correlation Between Antepartum Maternal Metabolism and Intelligence of Offspring. New England Journal Of Medicine. 325:911-16. 1991.

The children of 'true' diabetics, gestational diabetics, and normoglycemic women were given mental development and intelligence tests at ages 2, 3, 4, and 5. Even after correcting for possible confounding factors like socioeconomic status, etc. their scores correlated inversely with third-trimester levels of ketones. "The association between ketonemia in mothers...and lower IQ in their children speak for the need for continued efforts to avoid ketoacidosis and accelerated starvation in all pregnant women."

Diabetes and Pregnancy, ACOG Technical Bulletin (An Educational Aid to Obstetrician-Gynecologists), #200--Decemeber 1994.

The definitive summary from the American College of Obstetricians and Gynecologists; it covers pre-existing diabetes in pregnancy as well as gestational diabetes. Technical but still readable. This is the 'bible' many doctors rely on for advice, and represents the current standard of care in the field. A must-read for those seriously interested in the subject.


Coetzee, E.J. et al. Ketonuria in Pregnancy with Special Reference to Calorie-Restricted Food Intake in Obese Diabetics. Diabetes. 29:177. 1980.

Naeye, R.L., Chez, R.A. Effects of Maternal Acetonuira and Low Pregnancy Weight Gain on Children's Psychomotor Development. American Journal of Obstetrics and Gynecology. 139:189-93. 1981.




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