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Self-monitoring of blood glucose (SMBG) is an important component of modern therapy for diabetes mellitus. SMBG has been recommended for people with diabetes and their health care professionals in order to achieve a specific level of glycemic control and to prevent hypoglycemia. The goal of SMBG is to collect detailed information about blood glucose levels at many time points to enable maintenance of a more constant glucose level by more precise regimens. It can be used to aid in the adjustment of a therapeutic regimen in response to blood glucose values and to help individuals adjust their dietary intake, physical activity, and insulin doses to improve glycemic control on a day-to-day basis.

SMBG can aid in diabetes control by:

Hypoglycemia, also called low blood sugar, occurs when your blood glucose (blood sugar) level drops too low to provide enough energy for your body's activities. In adults or children older than 10 years, hypoglycemia is uncommon except as a side effect of diabetes treatment, but it can result from other medications or diseases, hormone or enzyme deficiencies, or tumors.

Glucose, a form of sugar, is an important fuel for your body. Carbohydrates are the main dietary sources of glucose. Rice, potatoes, bread, tortillas, cereal, milk, fruit, and sweets are all carbohydrate-rich foods.

After a meal, glucose molecules are absorbed into your bloodstream and carried to the cells, where they are used for energy. Insulin, a hormone produced by your pancreas, helps glucose enter cells. If you take in more glucose than your body needs at the time, your body stores the extra glucose in your liver and muscles in a form called glycogen. Your body can use the stored glucose whenever it is needed for energy between meals. Extra glucose can also be converted to fat and stored in fat cells.

When blood glucose begins to fall, glucagon, another hormone produced by the pancreas, signals the liver to break down glycogen and release glucose, causing blood glucose levels to rise toward a normal level. If you have diabetes, this glucagon response to hypoglycemia may be impaired, making it harder for your glucose levels to return to the normal range.

Symptoms

Symptoms of hypoglycemia include

• hunger
• nervousness and shakiness
• perspiration
• dizziness or light-headedness
• sleepiness
• confusion
• increased activity or exercise
• excessive drinking of alcohol

Hypoglycemia can also happen while you are sleeping. You might

• cry out or have nightmares
• find that your pajamas or sheets are damp from perspiration
• feel tired, irritable, or confused when you wake up

Causes of Hypoglycemia

In people taking certain blood-glucose lowering medications, blood glucose can fall too low for a number of reasons:

• meals or snacks that are too small, delayed, or skipped
• excessive doses of insulin or some diabetes medications, including sulfonylureas and meglitinides (Alpha-glucosidase inhibitors, biguanides, and thiazolidinediones alone should not cause hypoglycemia but can when used with other diabetes medicines.)
• increased activity or exercise
• excessive drinking of alcohol

Prevention

Your diabetes treatment plan is designed to match your medication dosage and schedule to your usual meals and activities. If you take insulin but then skip a meal, the insulin will still lower your blood glucose, but it will not find the food it is designed to break down. This mismatch might result in hypoglycemia.

To help prevent hypoglycemia, you should keep in mind several things:

• Your diabetes medications. Some medications can cause hypoglycemia. Ask your health care provider if yours can. Also, always take medications and insulin in the recommended doses and at the recommended times.
• Your meal plan. Meet with a registered dietitian and agree on a meal plan that fits your preferences and lifestyle. Do your best to follow this meal plan most of the time. Eat regular meals, have enough food at each meal, and try not to skip meals or snacks.

Normal and target blood glucose ranges (mmol / L)
Normal blood glucose levels in people who do not have diabetes
Upon waking (fasting)					4.0-6.0mmol / L
After meals					4.0-8.0mmol / L
Target blood glucose levels in people who have diabetes
Before meals					5.0-7.0mmol / L
1 to 2 hours after the start of a meal					less than 10 mmol / L
Hypoglycemia (low blood glucose)					4.0 mmol / L

• Your daily activity. Talk to your health care team about whether you should have a snack or adjust your medication before sports or exercise. If you know that you will be more active than usual or will be doing something that is not part of your normal routine--shoveling snow, for example--consider having a snack first.
• Alcoholic beverages. Drinking, especially on an empty stomach, can cause hypoglycemia, even a day or two later. If you drink an alcoholic beverage, always have a snack or meal at the same time.
• Your diabetes management plan. Intensive diabetes management--keeping your blood glucose as close to the normal range as possible to prevent long-term complications--can increase the risk of hypoglycemia. If your goal is tight control, talk to your health care team about ways to prevent hypoglycemia and how best to treat it if it does occur.

Treatment

If you think your blood glucose is too low, use a blood glucose meter to check your level. If it is 70 mg/dL or below, have one of these "quick fix" foods right away to raise your blood glucose:

After 15 minutes, check your blood glucose again to make sure that it is no longer too low. If it is still too low, have another serving. Repeat these steps until your blood glucose is at least 70. Then, if it will be an hour or more before your next meal, have a snack.

If you take insulin or a diabetes medication that can cause hypoglycemia, always carry one of the quick-fix foods with you. Wearing a medical identification bracelet or necklace is also a good idea.

Exercise can also cause hypoglycemia. Check your blood glucose before you exercise.

Severe hypoglycemia can cause you to lose consciousness. In these extreme cases when you lose consciousness and cannot eat, glucagon can be injected to quickly raise your blood glucose level. Ask your health care provider if having a glucagon kit at home and at work is appropriate for you. This is particularly important if you have type 1 diabetes. Your family, friends, and co-workers will need to be taught how to give you a glucagon injection in an emergency.