From the time you wake up until you go to bed, it is essential to keep your blood sugar as stable as possible if you have diabetes.

Reasons: Over time, uncontrolled elevated blood sugar harms the blood vessels, kidneys, eyes and nerves, increasing the risk for heart attack, stroke, kidney failure, blindness and tissue damage that can require limb amputation.

New finding: Diabetes also is linked to dementia.

Despite these dangers, scarcely half of the 23 million Americans who have been diagnosed with diabetes have their disease under control. If you’re struggling, you can significantly improve your blood sugar control by eating the right foods and doing the right things at the right times of day.

THROUGHOUT THE DAY

It is key to eat foods that digest slowly, so blood sugar remains relatively stable… and avoid foods that are digested quickly, triggering rapid blood sugar spikes. This also helps control weight — an important factor because excess weight contributes to diabetes complications. Guidelines…

  • Have 40 grams (g) to 50 g of carbohydrates at each meal. Stick with mostly complex carbs (whole grains, vegetables, nuts)… limit refined carbs (cakes, white pasta). Check labels!
  • Avoid foods with more than 10 g of sugar per serving.
  • Have some lean protein every day — chicken, fish, lean beef, low-fat dairy, eggs, tofu. Most people get enough protein, so you do not need protein with each meal unless your doctor recommends this.
  • Limit starches (corn, peas, potatoes, sweet potatoes) to one serving per meal.
  • Limit fruit to two servings per day. A serving equals one small handheld fruit (peach, plum)… half an apple or half a banana… 12 grapes… one cup of strawberries… or one-half cup of blueberries, raspberries or diced fruit (such as melon). Avoid pineapples and dried fruits, which are high in sugar.

AT WAKE-UP TIME

Test your blood sugar before breakfast. If it is high, you may have eaten too many carbohydrates too close to bedtime the night before. Or your levels may have fallen too low during the night, so your liver released more glucose (sugar), causing a blood sugar “rebound.” Talk to your doctor — you may need to adjust your medication dosage and/or timing.

AT BREAKFAST

The morning meal helps get your metabolism running efficiently, so don’t skip it.

Ideal: One or two slices of whole-grain bread with a soft spread that contains cholesterol-lowering plant sterols, such as Smart Balance or Promise Activ… plus a two-egg vegetable omelet. It is fine to use whole eggs — but if you have high cholesterol, make your omelet with egg whites instead and limit egg yolks to two per week.

Another good choice: One cup of unsweetened or lightly sweetened whole-grain cereal that contains no more than 25 g of carbohydrates per cup, such as Cheerios or Product 19… plus one-half cup of blueberries and one cup of low-fat milk. Don’t be fooled into thinking that high-fiber necessarily equals healthful — you still must check labels to see if the food is too high in carbs.

Your doctor may advise you to take a dose of diabetes medication right before breakfast.

Also: If you have diabetic nerve damage, take 100 micrograms of vitamin B-1 daily. If you take blood pressure medication, morning is the best time because blood pressure typically is higher during the day than at night. If you plan to drive, test your blood sugar before leaving home.

MIDMORNING

A midmorning snack generally is not necessary unless your doctor advises you to have one (for instance, due to the type of insulin you take). However, if you start to feel weak or dizzy, have a snack that provides no more than 10 g of carbohydrates — for instance, a small tangerine, half a banana or two graham cracker squares.

AT LUNCH

Good choices include a sandwich, such as turkey, lettuce and tomato on whole-wheat bread… or sushi with rice (preferably brown).

Common mistakes: Eating too much (especially at restaurants)… choosing a fruit plate (too much sugar and no protein)… overdoing it on chips or condiments (which can be high in fat or sugar).

MIDAFTERNOON

Again, have a snack only if you feel weak or your doctor recommends it, and limit yourself to no more than 10 g of carbs.

Good choices: About 15 pistachios… 10 almonds… or one-third of an ounce of whole-grain crackers.

AT DINNER

Check your blood sugar before dinner. If you are on oral diabetes medication, take it just before your meal.

Dinner should include four ounces of lean protein… several generous servings of vegetables… and one serving of a starch. Have a green salad, but skip the high-carb, high-fat dressings. Instead, drizzle greens with lemon juice, balsamic vinegar, safflower oil and/or olive oil.

Limit: One alcoholic drink daily, consumed with a meal. Opt for five ounces of wine… 12 ounces of a low-carb beer, such as Miller Lite… or one ounce of distilled liquor (Scotch, vodka). Avoid mixed drinks, which often are high in carbs.

Dessert options: A scoop of low-carb, no-sugar-added ice cream… berries… two Lorna Doone cookies… or three Social Tea Biscuits.

IN THE EVENING

This is the best time to exercise to maximize muscle cells’ absorption of glucose. Strength training and stretching are good, but aerobic exercise is most important because it increases insulin sensitivity (cells’ ability to respond to insulin) for up to 14 hours. Each week, aim for two-and-a-half hours of moderate-intensity aerobic exercise, such as walking… or one-and-a-half hours of strenuous activity. For blood sugar control, 30-minute workouts generally are most effective. As part of your exercise regimen, consider tai chi. In one study, diabetes patients who did this martial art significantly lowered their blood sugar levels.

Caution: Ask your doctor before starting an exercise program. Test blood sugar before each workout. If it is below 100 milligrams per deciliter (mg/dL), have a snack before exercising. Do not work out when your blood sugar is higher than 250 mg/dL — when blood sugar is this high, exercise may elevate it even further. If you have retinopathy (damaged blood vessels in the retina), to protect vision, do not lift weights above eye level.

AT BEDTIME

If you are on long-acting insulin, a bedtime injection controls nighttime glucose levels. If you take cholesterol-lowering medication, do so now — it is most effective at night. Test your blood sugar at bedtime. If it is somewhat elevated (but not above 250 mg/dL), lower it with 10 minutes of moderate exercise.

Insomnia doesn’t raise blood sugar, but the stress it creates can.

To promote sleep: Turn off the cell phone, TV and computer at least 30 minutes before bedtime so your mind can quiet down. Take a warm bath (checking your feet for wounds or signs of infection, because diabetes often damages nerves in the feet).

Have you been told that you snore? Diabetes patients are prone to sleep apnea (repeated halts in breathing during sleep), which contributes to poor blood sugar control. Do you frequently get up at night to urinate? It could be a sign that your medication needs adjusting. If you have either symptom, tell your doctor.