Diabetes management requires awareness. Know what makes your blood sugar level rise and fall — and how to control these day-to-day factors.

By Mayo Clinic Staff

Keeping your blood sugar levels within the range recommended by your doctor can be challenging. That's because many things make your blood sugar levels change, sometimes unexpectedly. Following are some factors that can affect your blood sugar levels.

Healthy eating is a cornerstone of healthy living — with or without diabetes. But if you have diabetes, you need to know how foods affect your blood sugar levels. It's not only the type of food you eat but also how much you eat and the combinations of food types you eat.

What to do:

  • Learn about carbohydrate counting and portion sizes. A key to many diabetes management plans is learning how to count carbohydrates. Carbohydrates are the foods that often have the biggest impact on your blood sugar levels. And for people taking mealtime insulin, it's crucial to know the amount of carbohydrates in your food, so you get the proper insulin dose.

    Learn what portion size is appropriate for each type of food. Simplify your meal planning by writing down portions for the foods you eat often. Use measuring cups or a scale to ensure proper portion size and an accurate carbohydrate count.

  • Make every meal well-balanced. As much as possible, plan for every meal to have a good mix of starches, fruits and vegetables, proteins, and fats. It's especially important to pay attention to the types of carbohydrates you choose. Some carbohydrates, such as fruits, vegetables and whole grains, are better for you than are others. These foods are low in carbohydrates and contain fiber that helps keep your blood sugar levels more stable. Talk to your doctor, nurse or dietitian about the best food choices and the appropriate balance of food types.
  • Coordinate your meals and medications. Too little food in proportion to your diabetes medications — especially insulin — may result in dangerously low blood sugar (hypoglycemia). Too much food may cause your blood sugar level to climb too high (hyperglycemia). Talk to your diabetes health care team about how to best coordinate meal and medication schedules.
  • Avoid sugar-sweetened beverages. Sugar-sweetened beverages — including those sweetened with high fructose corn syrup or sucrose — tend to be high in calories and offer little in the way of nutrition. And because they cause blood sugar to rise quickly, it's best to avoid these types of drinks if you have diabetes.

    The exception is if you are experiencing a low blood sugar level. Sugar-sweetened beverages, such as soda, juice and sports drinks, can be used as an effective treatment for quickly raising blood sugar that is too low.

Physical activity is another important part of your diabetes management plan. When you exercise, your muscles use sugar (glucose) for energy. Regular physical activity also helps your body use insulin more efficiently.

These factors work together to lower your blood sugar level. The more strenuous your workout, the longer the effect lasts. But even light activities — such as housework, gardening or being on your feet for extended periods — can improve your blood sugar level.

What to do:

  • Talk to your doctor about an exercise plan. Ask your doctor about what type of exercise is appropriate for you. In general, most adults should exercise at least 30 minutes a day on most days of the week. If you've been inactive for a long time, your doctor may want to check your overall health before advising you. He or she can recommend the right balance of aerobic and muscle-strengthening exercise.
  • Keep an exercise schedule. Talk to your doctor about the best time of day for you to exercise so that your workout routine is coordinated with your meal and medication schedules.
  • Know your numbers. Talk to your doctor about what blood sugar levels are appropriate for you before you begin exercise.
  • Check your blood sugar level. Check your blood sugar level before, during and after exercise, especially if you take insulin or medications that lower blood sugar. Exercise can lower your blood sugar levels even a day later, especially if the activity is new to you, or if you're exercising at a more intensive level. Be aware of warning signs of low blood sugar, such as feeling shaky, weak, tired, hungry, lightheaded, irritable, anxious or confused.

    If you use insulin and your blood sugar level is below 100 milligrams per deciliter (mg/dL), or 5.6 millimoles per liter (mmol/L), have a small snack before you start exercising to prevent a low blood sugar level.

  • Stay hydrated. Drink plenty of water or other fluids while exercising because dehydration can affect blood sugar levels.
  • Be prepared. Always have a small snack or glucose tablet with you during exercise in case your blood sugar drops too low. Wear a medical identification bracelet when you're exercising.
  • Adjust your diabetes treatment plan as needed. If you take insulin, you may need to reduce your insulin dose before exercising or wait awhile after exercise to inject insulin. Your doctor can advise you on appropriate changes in your medication. You may also need to adjust treatment if you've increased your exercise routine.

Insulin and other diabetes medications are designed to lower your blood sugar levels when diet and exercise alone aren't sufficient for managing diabetes. But the effectiveness of these medications depends on the timing and size of the dose. Medications you take for conditions other than diabetes also can affect your blood sugar levels.

What to do:

  • Store insulin properly. Insulin that's improperly stored or past its expiration date may not be effective. Insulin is especially sensitive to extremes in temperature.
  • Report problems to your doctor. If your diabetes medications cause your blood sugar level to drop too low or if it's consistently too high, the dosage or timing may need to be adjusted.
  • Be cautious with new medications. If you're considering an over-the-counter medication or your doctor prescribes a new drug to treat another condition — such as high blood pressure or high cholesterol — ask your doctor or pharmacist if the medication may affect your blood sugar levels. Liquid medications may be sweetened with sugar to cover their taste. Sometimes an alternate medication may be recommended. Always check with your doctor before taking any new over-the-counter medication, so you know how it may impact your blood sugar.

When you're sick, your body produces stress-related hormones that help your body fight the illness, but they can also raise your blood sugar level. Changes in your appetite and normal activity may also complicate diabetes management.

What to do:

  • Plan ahead. Work with your health care team to create a sick-day plan. Include instructions on what medications to take, how often to measure your blood sugar and urine ketone levels, how to adjust your medication dosages, and when to call your doctor.
  • Continue to take your diabetes medication. However, if you're unable to eat because of nausea or vomiting, contact your doctor. In these situations, you may need to adjust your insulin dose or temporarily stop taking your medication because of a risk of hypoglycemia.
  • Stick to your diabetes meal plan. If you can, eating as usual will help you control your blood sugar levels. Keep a supply of foods that are easy on your stomach, such as gelatin, crackers, soups and applesauce. Drink lots of water or other fluids that don't add calories, such as tea, to make sure you stay hydrated. If you're taking insulin, you may need to sip sugar-sweetened beverages, such as juice or a sports drink, to keep your blood sugar level from dropping too low.

The liver normally releases stored sugar to counteract falling blood sugar levels. But if your liver is busy metabolizing alcohol, your blood sugar level may not get the boost it needs from the liver. Alcohol can result in low blood sugar shortly after you drink it and for as many as 24 hours more.

What to do:

  • Get your doctor's OK to drink alcohol. Alcohol can aggravate diabetes complications, such as nerve damage and eye disease. But if your diabetes is under control and your doctor agrees, an occasional alcoholic drink is fine. Moderate alcohol consumption is defined as no more than one drink a day for women of any age and men over 65 years old and two drinks a day for men under 65. One drink equals a 12-ounce beer, 5 ounces of wine or 1.5 ounces of distilled spirits.
  • Don't drink alcoholic beverages on an empty stomach. If you take insulin or other diabetes medications, be sure to eat before you drink or drink with a meal to prevent a low blood sugar level.
  • Choose your drinks carefully. Light beer and dry wines have fewer calories and carbohydrates than do other alcoholic drinks. If you prefer mixed drinks, sugar-free mixers — such as diet soda, diet tonic, club soda or seltzer — won't raise your blood sugar.
  • Tally your calories. Remember to include the calories from any alcohol you drink in your daily calorie count. Ask your doctor or dietitian how to incorporate calories and carbohydrates from alcoholic drinks into your diet plan.
  • Check your blood sugar level before bed. Because alcohol can lower blood sugar levels long after you've had your last drink, check your blood sugar level before you go to sleep. If your blood sugar isn't between 100 and 140 mg/dL (5.6 and 7.8 mmol/L), have a snack before bed to counter a drop in your blood sugar level.

Changes in hormone levels the week before and during menstruation can result in significant fluctuations in blood sugar levels. And in the few years before and during menopause, hormone changes may result in unpredictable variations in blood sugar levels that complicate diabetes management.

What to do:

  • Look for patterns. Keep careful track of your blood sugar readings from month to month. You may be able to predict fluctuations related to your menstrual cycle.
  • Adjust your diabetes treatment plan as needed. Your doctor may recommend changes in your meal plan, activity level or diabetes medications to make up for blood sugar variation.
  • Check blood sugar more frequently. If you're likely approaching menopause or experiencing menopause, talk to your doctor about whether you need to monitor your blood sugar level more often. Symptoms of menopause can sometimes be confused with symptoms of low blood sugar, so whenever possible, check your blood sugar before treating a suspected low to confirm the low blood sugar level.

Most forms of birth control can be used by women with diabetes without a problem. However, oral contraceptives may raise blood sugar levels in some women.

If you're stressed, the hormones your body produces in response to prolonged stress may cause a rise in your blood sugar level. Additionally, it may be harder to closely follow your usual diabetes management routine if you're under a lot of extra pressure.

What to do:

  • Look for patterns. Log your stress level on a scale of 1 to 10 each time you log your blood sugar level. A pattern may soon emerge.
  • Take control. Once you know how stress affects your blood sugar level, fight back. Learn relaxation techniques, prioritize your tasks and set limits. Whenever possible, avoid common stressors. Exercise can often help relieve stress and lower your blood sugar level.
  • Get help. Learn new strategies for coping with stress. You may find that working with a psychologist or clinical social worker can help you identify stressors, solve stressful problems or learn new coping skills.

The more you know about factors that influence your blood sugar level, the more you can anticipate fluctuations — and plan accordingly. If you're having trouble keeping your blood sugar level in your target range, ask your diabetes health care team for help.

Jun. 10, 2014