Short post today on a new study suggesting that restricting carbohydrates in women with gestational diabetes mellitus (GDM) does not reduce their chances of needing insulin to control blood sugar during pregnancy. Spanish researchers randomly assigned 152 women with GDM to a control diet or a "low carbohydrate" diet. Each of the diets contained at least 1800 calories. The control diet contained 55% of calories from carbohydrate. And the "low carbohydrate" diet? It specified 40% of calories as carbs, or at least 180 grams. Definitely not low-carb, and significantly more than most of these women need, given the increased insulin resistance that is the hallmark of GDM. In addition, compliance was measured with three-day food records kept by the participants in their own homes rather than in a metabolic ward or other controlled setting where the amount of carbs actually consumed could be accurately assessed. The women's food records indicated they consumed between 155-191 grams of carbs daily; however, it's generally accepted that most people tend to underreport the amount of food they eat. The researchers concluded that a low-carbohydrate diet does not reduce insulin needs, but this is misleading given that this diet contained considerably more carbs than the women should have been advised to eat.
I've read other studies looking at similar "low carbohydrate" diets that actually weren't low enough to be therapeutic. Part of the problem is that there's no universally accepted definition of that term, but in my opinion, up to 190 grams of carbohydrate daily really seems like a stretch. Had these women been prescribed a diet containing less than 100 grams instead, I'm fairly confident the number requiring insulin would have been much lower than those following the control diet. I suspect they would have also had an easier time maintaining a healthy rate of weight gain during their pregnancies. Unfortunately, given that the media often only report the "conclusions" in research abstracts, the take-home message will be that carb restriction doesn't decrease the need for insulin in GDM, so there's no reason to try it. And that's a shame, because we know that decreasing carbohydrates does lower insulin requirements, provided that the amount consumed is low enough to keep blood sugar at a healthy level. 40% of caloric intake clearly exceeds that limit. References 1. Morena-Castilla C, et al. Low-carbohydrate diet for the treatment of gestational diabetes: a randomized controlled trial. Diabetes Care. e-published ahead of print April 5, 2013 do1:30.2337/dc12-2714
21 Comments
Whew! Your headline (theirs, really) misled me. I thought you were endorsing this line of baloney. In reality, you were as skeptical -- dismissive, actually, of this report as I am. And, of course, I also agree with your conclusion wrt the press take on this study. It will "feed" the notion that (real) low-carb does not benefit the GDM patient. I believe Howard Feinman and/or Richard Bernstein made an attempt to define LC and VLC and VLCKD a few years ago in a paper they published, perhaps in Diabetes Today or some other journal that Bernstain at least is on the Advisory Board of. I will try to find it for you.
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6/10/2013 12:45:03 am
Thanks, Dan! Sorry if the title was confusing. Glad you kept reading and discovered that I wholeheartedly endorse carb restriction for women with GDM, as well as all other people with diabetes. I'm pretty sure II have the paper that Dr. Feinman and Dr. Bernstein published with the various criteria for very-low-carb, low-carb, and moderate carb, but thanks so much for the offer. The thing is, those definitions still aren't agreed upon by everyone, which is why the researchers were able to characterize 180 grams as "low carbohydrate."
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6/10/2013 12:26:12 am
Great post, Franziska. Yeah, 40% carbs is more like Barry Sears' Zone diet; low carb proper would probably be about half of that. Someone should really try to define this! (like the BMI cutoffs.) Maybe calorie percentages aren't the most important/useful indicator of diet quality, but cutoffs would be useful for the media and even researchers so that we're all on the same page!
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6/10/2013 12:40:26 am
Thanks so much, Bill! I did find an article by Dr. Richard Feinman proposing the following definitions for various levels of carb restriction. I like these and hope they'll soon be adopted by all:
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Gerri
6/10/2013 06:14:15 pm
Hard to believe 180-190 carbs would qualify for any definition of LC. Makes me question if this study was intentionally designed to prove the outcome. Indeed, the headline will send the message, the wrong message, like the ACCORD study.
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Anna
6/11/2013 02:51:11 am
I must be an anomaly because I managed to avoid insulin use with a low carb diet while I had GDM. So I guess it only worked for me!
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6/11/2013 05:47:55 am
Hi Anna,
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Gina Whiteley
6/14/2013 07:11:17 am
Hi Franziska,
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6/14/2013 09:57:45 am
Thanks so much for your comments, Gina!
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R. Smith
9/9/2013 09:37:08 pm
Hi Franziska, Diabetes Dietitian from Australia here again. There were actually a couple of concerning studies in the early 1990s correlating 3rd trimester ketosis in DM and non-DM with lower intellegence and motor proficiency scores in the offspring at ages 2-9 years (Rizzo et al N Engl J Med 1991; 325:911-916 and Am J Obstet Gynecol. 1995 Dec;173(6):1753-8). There's been little research since then, but they are the papers behind the "avoid ketosis" statements in multiple papers&position statements on GDM nutrition since.
Lilian
1/11/2014 10:52:17 pm
Thank you for your input R. Smith, which is similar to my experience. Having been diagnosed with gestational diabetes and being on a low carb diet for around 1 month, I can testify that I have indeed lost weight resulting in tiredness and concentration loss, and feeling hungry all the time, and what's more the baby has appeared smallish on the 32 weeks scan... Also I have noticed that low carb meals at night do result in higher glucose levels in the morning. 6/18/2013 02:10:57 am
This sort of malarkey is an old Navaho Indian trick (no disrespect to Navaho native Americans) A so called lowcarb diet is often anything but. The same game is played with fats. I have lost count of negative fat studies and trials, but when checking the small print, trans fats have been included in the diet used. Trans fats have played a major part in metabolic disease and obesity in my opinion. As have refined carbs and so many foods now loaded with sugar and HFCS. A lowcarb diet done properly harms no one, indeed it has been the salvation of many, especially diabetics. For me a lowcarb diet is around 50 grams of carb per day. More than enough to stay fit and healthy.
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6/18/2013 05:51:27 am
Thanks so much for commenting. You're so right on all points!
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6/18/2013 02:22:26 am
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6/18/2013 05:54:25 am
Yes, I've read about Dr. Wortman's wife and also Dr. Andreas Eenfeldt's wife following LC and giving birth to very healthy and happy daughters. The pic of Jay's daughter is absolutely adorable!
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9/9/2013 11:09:22 pm
@ R. Smith,
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R. Smith
1/12/2014 05:48:44 pm
Hi Lilian, yes . . this tendency to undereat in response to GDM diagnosis is widespread. I see multiple patients every week doing this. But paradoxically, there are clear links between small for gestational age babies and insulin resistance/obesity/cardiovascular disease in later life (If interested, see BBC documentary on utube: "The 9 months that made you"). So undereating may well be just as problematic as overeating in the life long effects on that baby.
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1/12/2014 08:55:43 pm
Hi RS Smith,
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Joy
10/29/2017 01:14:12 pm
Third pregnancy, first time with GD here: Read all the comments and appreciate the multiple view points. I tried low carb dieting in fhe past and ended up with reduced seratonin production resulting in deprressive episodes. I’ve also found the tendency to undereat to be a burden. Instead of clinging to some extreme formula of ‘’correct’’ eating, I’m going to try a more balanced diet and keep track of my readings. One thing that’s clear is that different people need different diets at times.
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10/29/2017 05:53:34 pm
Hello, Joy,
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