How food affects
blood glucose levels

It has long been said that a meal plan that is well followed is the cornerstone to blood glucose control. This statement still rings true, even with the onslaught of new diabetes pills, quick-acting insulin, and high-tech blood glucose meters. In fact, healthy eating is the cornerstone not only to controlling blood glucose, but also to achieving weight loss and controlling blood lipids (total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides). In this feature we will focus on the impact that food has on blood glucose.

Since 1921, when insulin first became available, the recommendations for what people with diabetes should eat and how often to eat have changed dramatically. In the past, people with diabetes were not supposed to eat sugar and sweets, and it was recommended that they eat every few hours to keep their blood glucose levels from getting too low. But these recommendations have changed.

So, what are today's diabetes nutrition recommendations?

The American Diabetes Association nutrition experts revised their guidelines in 1994. Generally speaking, these guidelines reflect the way that all Americans should eat. Simply stated: it's healthy eating. There's no need to purchase special foods or to prepare foods differently for people with diabetes. And all family members will benefit from eating "diabetes style." We will discuss the recommendations of the American Diabetes Association and offer tips to help you put them into action.

If you'd like to review the guidelines in full, they can be found by clicking here.

What's Recommended?

Here are the ADA’s recommendations:

Eat a Moderate Amount of Protein
Aim for 10% to 20% of your calories. Select more non-animal sources of protein.

Americans eat about 14% to 18% of their calories as protein, which is within the recommended range. However, they favor animal sources of protein (meat, poultry, seafood, eggs, and dairy foods). Grains, nuts, beans, and vegetables are plant-based or non-animal proteins. They contain smaller amounts of protein per serving, as well as less total fat, less saturated fat, and less cholesterol.

The Recommended Dietary Allowance (RDA) for protein for adults is 0.4 grams/pound of body weight/day (or 0.8 grams/kg of body weight/day). That's about 60 to 65 grams of protein for the average male and about 50 to 55 grams of protein for the average female. The American Diabetes Association recommends reducing protein intake to no more than the RDA of 0.4 grams/pound of body weight/day if people with diabetes begin to develop kidney problems.

So, what's the bottom line? Eat a moderate amount of protein -- shoot for the RDA. If you have evidence of kidney disease, strive to match the RDA. And choose more vegetable sources of protein. You'll eat less total fat, less saturated fat, and less cholesterol. For people with evidence of kidney disease, some research suggests that eating vegetable protein rather than animal protein, or eating them in equal amounts, can delay the progression of kidney disease.

Practical tips:

  • Limit servings of meat, poultry, or seafood to two 3-ounce cooked servings per day.
  • Eat a few meals each week with no meat, poultry, or seafood. Opt for burritos filled with beans and rice,
      a vegetable and grain casserole, or vegetable lasagna.
  • Prepare dishes that s-t-r-e-t-c-h protein: stir-fries, meat sauces for pasta, or stews.
  • Pile on less meat in sandwiches and substitute lettuce, tomatoes, cucumbers, sprouts,
      or avocado to keep the sandwich stuffed.
  • Eat Less Fat
      Aim for about 30% of your calories.

Eat less saturated fat

Fat should comprise no more than 10% of your calories. It is now well known that saturated fat in the diet raises blood cholesterol, and high blood cholesterol is a risk factor for heart disease. It is also well documented that people with diabetes have an increased incidence and earlier onset of heart disease. So, what foods contain saturated fat? Mainly, animal sources of protein and full-fat dairy foods (whole milk, regular cheese, and butter). Other items that contain saturated fat are the so-called tropical oils -- coconut, palm, and palm kernel -- and foods with hydrogenated or "trans" fats. These fats are found in margarine, crackers, cookies, and snack foods.

Limit dietary cholesterol to no more than 300 milligrams a day. And what foods contain cholesterol? Foods that also contain saturated fat -- animal sources of protein and full-fat dairy foods. But there are a few big cholesterol carriers that are not high in saturated fat -- organ meats, shrimp, calamari (squid), and egg yolks.

Practical Tips

  • Choose lean cuts of meat, trim off fat, and "cook lean" -- broil, roast, grill, or poach.
  • Buy fat-free and low-fat milk and yogurt.
  • Remove and discard poultry skin.
  • Lighten up on cheese and choose part-skim, reduced fat, and light varieties.
  • Limit foods that contain hydrogenated and partially hydrogenated fat in the ingredient list. (Keep in mind:  Practicing the tips under the protein recommendation will also help you eat less total fat, less saturated fat,  and less cholesterol.)
  • Eat less polyunsaturated fat -- no more than 10% of your calories. Polyunsaturated fats lower total blood  cholesterol, but they lower the body's good cholesterol (HDL) at the same time. Vegetable, corn, and  safflower oils contain mostly polyunsaturated fats.

Eat more monounsaturated fat (10% to 15% of your calories). Of all the fats we eat, monounsaturated fats are now considered the "good guys." Olive and canola oils contain mostly monounsaturated fats. They help lower total blood cholesterol without lowering HDL cholesterol. But, don't go overboard! Monounsaturated fats still have the same number of calories as other fats.

Practical tips:

  • Stock the pantry with olive oil or canola oil; these are mainly monounsaturated fats. 
  • Skip the vegetable, corn, and safflower oils.
  • Sprinkle a few peanuts, almonds, or olives on salads or casseroles, or just chew a few now and then. (But -keep in mind that nuts and olives are loaded with calories.)
  • Put slices of avocado on salads or sandwiches.
  • Buy olive-oil-based or canola-oil-based salad dressings and canola-oil-based margarines or mayonnaise.  Or make your own salad dressing with these oils.

Eat More Healthy Carbohydrates

  • Choose more whole grains, fruits, and vegetables.
  • The amount of carbohydrate you eat should be based on your eating habits and your blood glucose and blood lipid goals. Let's review what foods contain carbohydrate. The main sources of carbohydrate are:
    • Grains
    • Beans
    • Starchy vegetables
    • Breads
    • Cereals
    • Rice
    • Pasta (6 or more servings a day)
    • Vegetables (3 to 5 servings a day)
    • Fruits (2 to 4 servings a day)
    • Dairy foods (2 to 3 servings a day)
    • Once foods containing carbohydrates pass your lips, they are digested, and 100% of the carbohydrate is  broken down into glucose.
    • Enjoy Sweets on Occasion

The rather startling news from the 1994 American Diabetes Association nutrition guidelines was that regardless of the food source, all carbohydrates raise blood glucose to about the same degree and at about the same rate. This means that if you eat the same amount of carbohydrate as either gumdrops or potatoes, your blood glucose will rise about the same. The belief that sugars raise blood glucose faster than starches simply doesn't hold up in the research. However, sugary foods and sweets contain sugar and calories, and possibly fat and cholesterol, but little or no nutrition. You can enjoy sweets on occasion. But including them in your meal plan depends on your personal nutrition and diabetes management goals.

How Does Carbohydrate Affect Your Blood Glucose Level?

The rate at which carbohydrate raises your blood glucose level is affected by:

  • What you eat with the carbohydrate
  • How quickly you eat
  • How much fiber is in the meal
  • Your pre-meal blood glucose level
  • How your diabetes medication works or how quickly it works
  • How quickly your body digests different foods

Let's make it simple. It is the total amount of carbohydrate you consume that has the greatest impact on your blood glucose levels. To keep your blood glucose levels in control, focus on carbohydrate. Eat similar amounts of carbohydrate at your meals each day, unless you adjust your diabetes medication based on your carbohydrate intake. To boost your intake of critical nutrients, eat more high-fiber carbohydrates like whole-grain breads and cereals, beans, and starchy vegetables. Also, eat more fruits and vegetables.

Practical tips:

  • When you read the Nutrition Facts on a food label, focus on the Total Carbohydrate rather than the sugars. -Sugars are counted as part of the total carbohydrate. Besides, the sugars include not just added sugars  like corn syrup and honey, but also the natural sugars found in foods -- for example, the lactose in milk  and the sucrose in fruit.
  • Look at the grams of dietary fiber on food labels. Try to get at least 3 grams of fiber per serving for breads  and 5 grams for cereals.
  • Cook with grains -- couscous, quinoa, bulgur, barley, orzo, or risotto. Prepare them in low-fat ways. Add  them to salads, casseroles, soups, and stews.
  • Eat more starches and vegetables, but cook and top them the low-fat way. Use light sour cream or cream  cheese, non-fat yogurt, mustard, lemon, vinegar, or tomato sauce.
  • Prepare enough salad for several days and put it in a plastic container. Then reach in for a handful.
  • Keep raw vegetables cut up and ready-to-eat with sandwiches, as a salad topper, or as a snack with light  salad dressing.
  • Add fruit to your breakfast -- for example, banana on cold cereal, raisins in hot cereal, or juice with breakfast.
  • Add fruit to your lunch -- most fruits travel well and provide a refreshing and healthy complement to your lunch.

Individualization and Flexibility Are Key

Today's message is loud and clear -- your meal plan must be individualized and flexible enough to fit you and your lifestyle. Gone are the days when a pre-printed, one-size-fits-all meal plan was helpful. In addition, the diabetes exchange system is no longer the only method available for meal planning.

To help you achieve your diabetes goals, your meal plan should be based on
your food preferences, your schedule, and your blood glucose and blood lipid levels. In addition, your food, medication, and activity plans should consider your need for flexibility -- how much your life changes from day to day. For example, you may need more calories or less medication on the days you go to aerobics class or for a long walk. Or you may need different plans for weekdays and weekends or for days you travel versus those you spend at your desk. Today this flexibility is possible.

To develop an individualized and flexible meal plan, you should work with a dietitian who has diabetes expertise or with a diabetes educator on an ongoing basis. This site is here to provide you with resources and to help you learn how to apply the guidelines you receive from your dietitian or diabetes educator.

Two good sources for diabetes educators and education programs are:

American Association of Diabetes Educators
American Diabetes Association recognized education programs

Let's Be Realistic

Okay, you've got the theory under your belt. That's the easy part. Doing it is the hard part. No doubt staying on track with what, how much, and when to eat is the toughest aspect of managing diabetes. To ease the burden, don't think of changing your eating behaviors and food choices as a "presto chango" deal. Think of it as a long-term process; it may take years to make and feel comfortable with the changes, and that's okay. But you've got to get started.

A good place to start is to take an inventory of your eating habits. Keeping a food record for a few days will help you identify your pitfalls -- as long as you are honest. Use this insight to establish your personal nutrition goals. If you have type 2 diabetes, your first goal may be weight loss. You might achieve this goal by focusing on the two or three habits you are now ready to change. Look at your inventory. You may find that your fat intake is sky high. The realistic behavior changes you are ready to make could be:

  • Measuring out salad dressing rather than just pouring
  • Eating smaller portions of meat -- 4 to 5 ounces for starters rather than 7 to 8 ounces
  • Switching from whole milk to 1% milk
  • In addition, you could also be ready to set the realistic behavior change of walking for 20 minutes three times a week.

Blood Glucose Monitoring: Your Feedback Loop

Does eating breakfast before you leave for work help prevent mid-morning hypoglycemia? Does less snacking at night keep your fasting blood glucose closer to normal? Or is your fasting blood glucose high no matter what you eat?

Blood glucose monitoring is your feedback loop. It helps you observe how your blood glucose levels are affected by the food you eat, when you eat, your medications, and your activities. To see how your blood glucose is affected by the food you eat, test your blood 2 hours after eating. With this information in hand, you can make changes in one or more aspects of your diabetes management plan, or you can consult with your doctor, dietitian, or diabetes educator about any needed changes.

It is now known, beyond a shadow of a doubt, that the key to staying healthy with diabetes is good blood glucose control, day after day and year after year. And the key to good blood glucose control is a healthy eating plan, designed with you and for you, that matches your food preferences, your lifestyle, your blood glucose and blood lipid levels, the action of your diabetes medications, and your activities.

-American Diabetes Association. Nutrition recommendations and principles for people with diabetes mellitus. Diabetes Care [serial online]. 2000;23(1). Available at: Accessed July 3, 2002.

-American Diabetes Association. Position statement: evidence-based nutrition principles and recommendations for the treatment and prevention of diabetes and related complications. Diabetes Care [serial online]. 2000;25:S50-S60. Available at: Accessed July 3, 2002.

This article was written by Hope S. Warshaw, MMSc, RD, CDE, a best-selling author whose most recent book is The American Diabetes Association Guide to Healthy Restaurant Eating.

— Revised July 2002