Dear Colleague,
I read. I listen...diabetes blogs, magazine articles, professional group list servs, websites, Facebook posts, tweets on Twitter, and much more. Each day, I get more concerned about the laser-like focus and singular attention in the diabetes universe on the portrayal of carbohydrates as the omnipotent nutrient. With the support of research and current management guidelines, it's time for me to review the State of the Nutrient: Carbohydratehere.
I must conclude, the state of this important macronutrient is in crisis. Glycemic ControlMyopia, as I call it, has taken root. It's unhealthy and unhelpful.But first, a definition of Glycemic Control Myopia. It includes limiting (and advocating for) total carbohydrate consumption below 40-45% of calories (or significantly lower) and placing laser-like focus for people with diabetes (PWD) on carbohydrate intake and glycemic control. Sure, it's understandable that when PWD learn that the carbohydrate from foods is what contributes most to the rise in post-prandial glucose levels, they think severe carbohydrate restriction is goal number one. And if they search on "diabetes diet" on the Internet, they'll find plenty of information to perpetuate this notion which is unsupported by research.
Understandable, but it's our role as practitioners, when given the opportunity (which is not nearly frequently enough), to provide accurate evidence-based information about carbohydrates. The reality is that if a PWD, type 1 or 2, has sufficient insulin available at the time of carbohydrate consumption, either from endogenous or exogenous insulin, they should be quite able to control their post-prandial glucose levels. Bottom line: post-prandial glycemic control requires a balance of digestible carbohydrate intake and insulin availability. And yes, today we know that additional hormones are involved in glycemic control – glucagon, amylin, incretins and more.
To my four concerns about Glycemic Control Myopia...
Concern #1: Carbohydrate Restriction Can Add Up to Unhealthy Eating
As I recapped in my January 2013 NutriZine Wylie-Rosett et al. in their research editorial, discussed how our focus on carbohydrates and carbohydrate counting is promoting unhealthy eating among youth with type 1 diabetes (T1D).1,2 I'll add here the findings of Mehta, et al's small study from Joslin Diabetes Center, Boston, MA in youth with T1D and parents participating in focus groups.3 Results show that parents and youth qualified their perceptions of "healthful eating" by focusing on a food's glycemic effect. As such, foods resulting in larger or more erratic postprandial glycemic excursions were considered less healthful. The study found that for both youth and parents, an emphasis on carbohydrate quantity over quality may distort beliefs and behaviors regarding "healthful eating."
Reality is that Americans have been eating about 45-50% of calories as carbohydrate for years4 (albeit with an increase in total calories and less nutrient dense forms of carbohydrate over the last few decades).4People with diabetes have been shown to eat about 44 to 46%.5 Regarding our sources of carbohydrates as Americans, we need to direct our focus on quality, not quantity. We eat excess added sugars (~22 tsp/day)6 and insufficient amounts of nutrient-dense sources of carbohydrates – fruits, vegetables, whole grains, legumes and low fat dairy foods – critical foods in a healthy eating pattern (more about this below). So, rather than trying to get PWD to focus on the quantity of carbohydrates they eat, shouldn't we encourage them to focus on quality? Research by Sacks et al., showed that over the long haul people in the POUNDS LOST weight loss study gravitated back to a macronutrient balance in which the carbohydrates accounted for 43 to 53% of calories.7 Yes, within the range that most people with diabetes and Americans eat.
Research also shows that the greatest predictor of glycemic control is the reduction of total energy (calorie) intake, not the reduction of total carbohydrate consumption (or other significant changes in macronutrient distribution).5 And since Americans consume a large portion of their non-nutrient dense excess calories from added sugars, doesn't it make sense to put our focus on decreasing consumption of these to achieve total energy reduction and increasing consumption of nutrient dense sources of carbohydrates?
As educators/providers, we need to reign in this low carbohydrate zealotry and offer, well yes, some basic nutrition education and knowledge and guidance about just what is healthy eating such as:
- Our calories are provided in foods and beverages which contain varying amounts of carbohydrate protein and fat (as I teach – packages of nutrients). Foods aren't "carbs", they contain carbohydrate.
- An explanation of macronutrient balance. If one eats less carbohydrate, then they may (over the course of time) eat more protein and fat. And these sources of protein and fat may, based on common American food choices and preferences, provide more saturated fats. And what we know about saturated fat is that it causes insulin resistance, which is a central feature in prediabetes and T2D.5 The Dietary Reference Intake and Dietary Guideline recommendation for carbohydrate is 45- 65% of calories.4,8 According to the 2010 Dietary Guidelines for Americans4, it's difficult, especially at lower calorie levels (<1500 calories), to eat sufficient amounts of many of the shortfall nutrients when eating at the low end (~45%) of this range of carbohydrates: dietary fiber, potassium, calcium, magnesium (and other minerals) and vitamin A,C,D (and other vitamins);. The Dietary Guidelines 2010, go on to state related to achieving weight loss, "Diets that are less than 45 percent carbohydrate or more than 35 percent protein are difficult to adhere to, are not more effective than other calorie-controlled diets for weight loss and weight maintenance, and may pose health risk, and are therefore not recommended for weight loss or maintenance."4
And isn't another important factor in our work giving the PWD we counsel advice they can follow day in, day out, not just for a couple of weeks? Yes, they will have diabetes the rest of their life.
Concern #2: Carbohydrate Restriction Doesn't Assure Glycemic Control
Yes, sounds counterintuitive. However research DOES NOT show that restricting carbohydrate necessarily improves glycemic control. Consider Delahanty, et al.'s review of the dietary data from 532 of the intensively-treated DCCT participants. Participants who consumed a mean carbohydrate intake of 56% of calories had a significantly lower A1C, 7.08%, compared to an A1C of 7.47%, for participants whose mean carbohydrate intake was 37% of calories.9 People who ate less carbohydrate ate more total fat and saturated fat.Concern #3: Carbohydrate Restriction Aids and Abets Medication Avoidance
The focus here is on T2D, particularly those PWD with fewer years of diabetes duration. There seems to be an overarching notion that BG lowering medications should be avoided (despite having to eat unhealthfully, very low carbohydrates, to maintain glycemic control) for as long as possible and that having to take one or more medication is paramount to failure or defeat. This notion catapults me back to my early years in diabetes when we only had two categories of BG lowering medications – sulfonylureas (1st generation) and insulin (mainly NPH and regular), and not the much wider variety of medications available today.
We've come a long way baby, as the saying goes, with BG lowering medications. In addition, we now know that prediabetes/T2D is progressive and at diagnosis of T2D people have already lost 50 – 80% of their beta cell mass and/or cells. Relevant to this population the 2012 ADA/EASD Management of Hyperglycemia in Type 2 Diabetes position statement, encourages starting an insulin sensitizer (most commonly metformin) in most people with T2D unless they are highly motivated to engage in lifestyle change for 3-6 months to determine success with glycemic control before initiating medication.10
Yes, I've been accused of being a drug salesman. I can assure you I'm not! I'm a diabetes educator who believes that being honest with clients about our current understanding of T2D disease progression, healthy eating (a la U.S. Dietary Guidelines) and the critical importance of glucose, lipid and blood pressure control over time to prevent/delay diabetes complications. We owe it PWD with T2 to let them know about the many new categories of BG lowering medications, how these are being use, and how they can help them stay healthy over time when initiated EARLY in their course of T2D.
And when it comes to people with T1D or their caregivers, it's important for us to make the point that no research to date shows that taking less insulin by limiting carbohydrate intake appears to have any long term health or glycemic control benefits. To achieve glycemic control the goal with insulin in T1D is to adjust prandial doses of rapid-acting insulin to match desired carbohydrate intake.11
Concern #4: Carbohydrate Restriction Potentiates Disease Tunnel Vision and Stands in the Way of Healthy Eating
By no means do PWD only have the disease diabetes. We know they, like all people, are at risk for other chronic diseases. In fact, all PWD are at greater risk for CVD. Research is accumulating to show that, due to the common thread of insulin resistance, people with T2D and prediabetes may be more prone to develop certain cancers, like breast (in post menopausal women)12, pancreas, colon and others. There's mounting evidence that the optimal eating plan for chronic disease prevention is one that is plant-based. That doesn't necessarily mean going vegetarian, but it does mean minimizing meats/protein-based foods (especially red and processed meats) and saturated fats and eating mainly carbohydrate-based, nutrient dense foods. That's certainly not low carbohydrate!
Educators need to widen the mindset of PWD and discuss how a healthy eating pattern with sufficient amounts of quality sources of carbohydrates can assist with control of diabetes as well as prevention/delay of other chronic diseases PWD are at greater risk for. To learn more I encourage you to sit back and watch our brand new lecture Diabetes and Cancer: What's the Connection? by Karen Collins, MS, RD, CDN, Nutrition Advisor, American Institute for Cancer Research. PRESENTdiabetes.com lectures come with FREE CE through the Academy of Nutrition and Dietetics Commission on Dietetic Registration (CDR) for nutrition professionals. Also all lectures on PRESENTDiabetes.com are approved for CE through the Mt. Sinai School of Medicine in New York and the CDR.
Yes, hopefully I've gotten your wheels turning and churning. I'm anxious to get your read of the research and your thoughts from your clinical practice and beyond. Please join me on eTalk to chat about the State of the Nutrient: Carbohydrate?
There you have it eat plenty of carbs and take your medications or you could end up like me suffering from Glycemic Control Myopia.
Graham
Edit to add this comment from Hope Warshaw re Richard Bernstein MD:
"Let's make sure we let science drive our clinical advice vs. diet books like South Beach or self-proclaimed physicians like Richard Bernstein, MD who has never published a research study (that I know of) testing and documenting his low-carb hypotheses re: glycemic control."
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