Source: Adi Benito, M.D. (Princeton Integral Endocrinology)
In the U.S. alone, 88 million adults (one third of the population) have prediabetes, a condition that without intervention, leads to type 2 diabetes within 5-10 years. In addition to prediabetes, certain characteristics increase our risk for type 2 diabetes. Those characteristics include a family history of diabetes mellitus; being of Hispanic, African American, American Indian, Asian-American, or Pacific Islander ethnicity, having a birth weight > 9lbs, having a history of diabetes mellitus during pregnancy, being overweight, having a history of polycystic ovarian syndrome (PCOS), age over 45 years, having high blood pressure, and poor sleep (either < 6 hours or > 9 hours per night). Likely stress, and social jetlag (the discrepancy of sleep hours between work days and non-work or free days) are also risk factors for the development of type 2 diabetes.
From nutrition to targeted exercise, adequate sleep, decreased stress, and social support groups, successful interventions to prevent diabetes encompass all aspects of life. Having a good social support system is key to successful lifestyle changes; and setting goal settings and participating in small groups are important for our success to modify dietary behaviors. Keeping in sync with our own circadian, natural rhythm might be as important as sleeping enough.
We know that diabetes mellitus can be prevented since the results of a pioneer study, the United States Diabetes Prevention Program (USDPP), were published in 2002. In this study, over 3,000 overweight men and women with prediabetes were randomly assigned to one of three groups; placebo, lifestyle and exercise, and metformin (a medication used to treat diabetes). Lifestyle and exercise involved eating less fat and fewer calories, and exercising for 150 minutes per week with intensive counseling. The lifestyle and exercise group fared better than the medication group in the prevention of diabetes. The lifestyle group achieved a weight loss of 7%, which resulted in a decrease in the risk of progression to type 2 DM by 58% over three years (for those over age 60, the risk reduction was 71%). Since the USDPP, other studies have shown similar findings.
Using Food in the Integrative Prevention of Diabetes:
Western diets have been associated with an increased risk of diabetes in men and in women. Western diets tend to include higher intakes of red and processed meats, sweets and desserts, fries, and refined grains. In particular, high (daily) consumption of red meat or processed meats increases the risk of developing diabetes.
On the other hand, healthy ways of eating, characterized by a high intake of fruits and vegetables, whole grains, fish and poultry, and low intake of red meat, processed foods, sugar-sweetened beverages, and starchy foods are consistently associated with the prevention of type 2 diabetes.
Several ways of eating have been evaluated for diabetes prevention:
- Low glycemic index. The low glycemic index diet includes carbohydrates and other foods with low glycemic index, which are defined as foods that cause a slow rise in sugar and insulin. A low glycemic index diet has been shown to reduce hemoglobinA1c (HbA1c), between 0.4 and 0.5%. HemoglobinA1c (HbA1c) is a marker of your previous 3-month average blood sugar, and a decrease of 0.5% in HbA1c is a good response and similar to what some medications can achieve, and can bring someone from prediabetes to normal. The data is inconclusive for the prevention of diabetes, but the American Diabetes Association states that when high in fiber, this type of diet can be encouraged. As we will see later, high fiber lowers the risk of type 2 diabetes.
- Mediterranean diet. The Mediterranean diet is the dietary pattern common to countries of the Mediterranean basin such as Greece, France, Italy and Spain. This way of eating eliminates pro-inflammatory fats, promotes a healthy balance of omega3/omega 6 fatty acids; it is high in fruits and vegetables, unsaturated fats, and fish but also includes grains, mostly with a low glycemic index, and includes moderate alcohol (mostly red wine) consumption. In essence, the Mediterranean diet is abundant in plant-based foods, minimally processed, and advocates for local, fresh seasonal produce, olive oil, low to moderate consumption of dairy products (milk and yogurt) and alcohol (with meals) and low consumption of red meat. The Mediterranean diet has been associated with a reduction of Hb A1c between 0.6 and 1%, and with an 83% reduction in the risk of diabetes. And following a Mediterranean diet helps weight loss, sugar levels, blood pressure, cholesterol, and markers of inflammation.
- The DASH (Dietary Approaches to Stop Hypertension) diet. The DASH diet was initially developed by the National Institutes of Health (NIH) to lower blood pressure. The DASH diet is rich in fruits, vegetables, and low-fat/nonfat dairy, and includes whole grains, nuts, beans and seeds. The DASH diet is low in fat, red meat, and sweets. The DASH diet is also rich in magnesium and fiber, in addition to potassium and calcium. Magnesium intake in food, has been inversely associated with the risk of developing type 2 diabetes. And so has fiber. When combined with weight loss and exercise, the DASH diet can lead to decreased insulin resistance, which is desirable. Insulin resistance is at the core of type 2 diabetes and leads to the inability of the body to bring sugar into the cells with a resulting high sugar in blood.
- Vegetarian diet. A vegetarian diet focuses on fruits and vegetables and foods low in saturated fats, and tends to be higher in fiber and lower in calories than other diets. A vegetarian diet has been associated with a reduction of 1.23% in HbA1c, a tremendous decrease, and it promotes weight loss. However, a vegetarian diet might need supplementation with vitamin B12, iron, zinc and some amino acids.
- Paleolithic diet. The paleolithic diet or “paleo” diet is based on lean meat, fish, fruits, vegetables, root vegetables, eggs, and nuts and the avoidance of processed foods, legumes (including peanuts), dairy, and grains. The paleolithic diet has been shown to reduce HbA1c by 0.4% and to improve glucose tolerance, lower blood pressure and increase HDL (our healthy cholesterol). This way of eating can also decrease waist circumference. It might be necessary to add calcium because of the lack of dairy products, unless dark green leafy vegetables are consumed.
Whether one decides to follow a particular way of eating should be an individualized decision. However, there is evidence for prevention of diabetes mellitus with high fiber, the introduction of healthy fats (such as walnuts and omega-3 fatty acids), and choosing low carbohydrate/low glycemic index foods. Foods of importance in the prevention of diabetes are those rich in fiber, those rich in polyphenols, and those rich in magnesium.
Fiber
Fiber in particular merits mention. Current daily recommendations by the Institute of Medicine are 25 grams and 38 grams of dietary fiber for women and men under 50, respectively. And data shows that in the US, we probably consume one third of the recommended fiber per day.
Fiber, soluble and fermentable in particular, such as what is found in avocados, oats, barley, Jerusalem artichokes, leeks, onions, garlic and other fruits (mostly berries) and vegetables (turnips, carrots, and asparagus), nuts and seeds improves weight and insulin sensitivity through several mechanisms, including increase in satiety, decrease in after meals sugar levels, improved insulin sensitivity, release of gut peptides, and modulation of gut bacteria.
Consumption of 13 grams (approximately 2 Tbsp) of ground flaxseeds daily has been shown to improve sugar control in 25 obese men and postmenopausal women with prediabetes.
Polyphenols
Polyphenols are a large family of plant-derived compounds with different chemical structures. Among polyphenols, we have anthocyanins which confer the red/blue color to berries, red bell peppers, red cabbage, and grapes. High intake of anthocyanins confers a 15% reduction in the risk of type 2 diabetes.
When eating blueberries more than twice per week or apples/pears five times per week (vs less than once per month), a 25% reduction in the risk of type 2 diabetes was seen.
Magnesium-Rich Foods
Low magnesium has been associated with insulin resistance and diabetes, and eating foods rich in magnesium decreases inflammation, improves blood pressure and blood sugar levels. Magnesium is important in over 300 metabolic reactions.
Foods rich in magnesium include green-leafy vegetables (spinach, kale, chard…), nuts (almonds, cashews) and seeds (pumpkin), legumes, whole grains, avocado and salmon. In several studies, the people with the highest consumption of magnesium in their diets had the lowest risk of developing type 2 diabetes.
When you eat and how you eat might be as important as what you eat. Our body metabolism changes throughout the day. A slice of bread consumed at breakfast leads to a lower sugar response and is less fattening than an identical slice of bread consumed in the evening.
In a weight-loss study published in the medical journal JAMA, the researchers noted that “The people who lost the most weight reported that the study had “changed their relationship with food.” They no longer ate in their cars or in front of their television screens, and they were cooking more at home and sitting down to eat dinner with their families, for example”.
People who cut back on added sugar, refined grains and highly processed foods while concentrating on eating plenty of vegetables and whole foods – without worrying about counting calories or limiting portion sizes – lost significant amounts of weight over the course of a year, regardless of diet.
In addition, for every lunch prepared at home during a week, the risk of type 2 diabetes decreases 2% and for every dinner 4%. And for those who ate between 11-14 home-prepared meals per week, the risk of developing type 2 diabetes was 13% lower than for those consuming 6 or less homemade meals per week.
Fasting and Time-Restricted Feeding
Time-restricted feeding or limiting food intake to an interval of 6-10 hours per day has been shown to improve weight, sleep, energy, blood pressure and appetite. In particular early time-restricted feeding (eating between 8am and 2pm or between 9am and 3pm) improved weight, insulin, blood pressure, and appetite. Remember that losing weight in turn decreases our risk of developing diabetes.
Studies on intermittent fasting (either alternate day fasting or fasting two days per week) however have not found consistent results. More promising is the “fasting-mimicking diet” invented by researcher Valter Longo. The fasting-mimicking diet is a plant-based diet, characterized by low-calorie, low-protein and low-carbohydrate (low sugars) but high- unsaturated fat followed for five consecutive days, once a month for at least three months.
The results of the studies to date are very intriguing and point to an improvement of sugar metabolism, protection of insulin production, improved gut microbiome, and lowering of inflammation.
Supplements
There are many supplements which promote sugar regulation. Of those, the only one with data to support diabetes prevention is curcumin, the main ingredient in turmeric. And of the supplements which help with sugar regulation, cinnamon can be consumed as food.
Cinnamon
Cinnamon is a spice rich in polyphenol compounds, tannins and coumarins. The energy of cinnamon is warm and dry. Two types of cinnamon have been studied in clinical trials; Cinnamomum zeylanicum (true cinnamon) and Cinnamomum cassia (false or Chinese cinnamon). Most studies used C. cassia. Recently, a safety concern has been raised with the consumption of C. cassia because of its coumarin contents and their potential liver toxicity. In laboratory studies, cinnamon lowers blood glucose and improves lipids.
The clinical studies on the effect of cinnamon on glycemic control have been mixed, though. In my review of all available studies, I concluded that the data is strongest for people with prediabetes or poorly controlled diabetes (HbA1c > 8%). Based on the available data, the recommended dose is 250 mg twice daily or 500 mg once daily of a water extract. If using powdered cinnamon bark, use 3 to 6 grams (equivalent to 2-4 tsp) per day, although some studies have shown benefits even at 1 gram per day (a bit less than a 1 tsp per day).
Curcumin
Curcumin is the main chemical in turmeric (Curcuma longa). Turmeric has been exalted for its antiinflammatory and antidiabetic properties. Current studies support the use of curcumin to delay the progression to type 2 diabetes. Dosage recommendations are 750 mg curcuminoids twice daily for at least three months. To exemplify how much turmeric this would represent, 1 tsp of turmeric contains 2.5 grams of turmeric and 60-100 mg of curcumin.
So, to reach a medicinal dose, between 15 and 25 tsp of turmeric would have to be consumed daily. Curcumin seems well tolerated, and the main side effects are nausea and diarrhea. Caution is advised if you have gallbladder disease or if you are taking blood thinners.
Chromium and Zinc
Chromium and zinc both have a role in sugar metabolism. There are no studies on the prevention of diabetes with chromium or zinc, but it is reasonable to include foods rich in chromium and zinc. Chromium is present in foodstuffs such as chicken, beef, fish, cheese, whole grains, dark chocolate, peanuts, brewer’s yeast, tea, beer, wine, and some fruits and vegetables (broccoli and green beans).
Zinc is abundant in red meat, chicken, oysters, legumes, nuts, whole grains and fortified-products. To maximize zinc absorption from vegetarian sources, food can be fermented, germinated (sprouted) and/or soaked (beans), maneuvers which decrease the phytate content known to decrease absorption of zinc.
Conclusion
In summary, healthy eating, and eating home-prepared meals lowers our odds of developing type 2 diabetes. Eating mindfully and eating within a shorter period of time improves sugar regulation and helps lower weight, which in turn helps us prevent type 2 diabetes. Researchers are still exploring whether fasting or fasting-mimicking diet might help in the prevention of diabetes.