Type 1 diabetes; Insulin-dependent diabetes; Juvenile diabetes
Insulin is essential for strict control of blood glucose levels in type 1 diabetes. Tight blood glucose control is the best way to prevent major complications in type 1 diabetes, including those that affect the kidneys, eyes, nerve pathways, and blood vessels. Intensive insulin treatment in early diabetes may even help preserve any residual insulin secretion for at least 2 years.
There are, however, some significant problems with intensive insulin therapy:
A diet plan that compensates for insulin administration and supplies healthy foods is extremely important. [For more information, see In-Depth Report #42: Diabetes diet.] Pancreas transplantation may eventually be recommended for patients who cannot control glucose levels without frequent episodes of severe hypoglycemia.
The goal of intensive insulin therapy is to keep blood glucose levels as close to normal as possible.
Glucose Goals for Patients with Diabetes
Blood glucose levels before meals
Less than 110 mg/dL
90 - 130 mg/dL for adults
100 - 180 mg/dL for children under age 6
90 - 180 mg/dL for children 6 - 12 years old
90 - 130 mg/dL for children 13 - 19 years old
Bedtime blood glucose levels
Less than 120 mg/dL
110 - 150 mg/dL for adults
110 - 200 mg/dL for children under age 6
100 - 186 mg/dL for children 6 - 12 years old
90 - 150 mg/dL for children 13 - 19 years old
Glycosylated hemoglobin (HbA1c) levels
4 - 6%
Less than 7%
Source: Standards of Medical Care In Diabetes -- 2008, American Diabetes Association.
Standard insulin therapy usually consists of one or two daily insulin injections, one daily blood sugar test, and visits to the health care team every 3 months. For strictly controlling blood glucose, however, intensive management is required. The regimen is complicated although newer insulin forms may make it easier.
There are two components to flexible insulin administration and a number of variations of insulin delivery for accomplishing them:
In achieving insulin control the patient must also take other steps:
Because of the higher risk for hypoglycemia in children, doctors recommend that intensive treatment be used very cautiously in children under 13 and not at all in very young children.
Insulin cannot be taken orally because the body's digestive juices destroy it. Injections of insulin under the skin ensure that it is absorbed slowly by the body for a long-lasting effect. The timing and frequency of insulin injections depend upon a number of factors:
Fast-Acting Insulin. Insulin lispro (Humalog) and insulin aspart (Novo Rapid, Novolog) lower blood sugar very quickly, usually within 5 minutes after injection. Insulin peaks in about 4 hours and continues to work for about 4 more hours. This rapid action reduces the risk for hypoglycemic events after eating (postprandial hypoglycemia). Optimal timing for administering this insulin is about 15 minutes before a meal, but it can also be taken immediately after a meal (but within 30 minutes). Fast-acting insulins may be especially useful for meals with high carbohydrates.
Regular Insulin. Regular insulin begins to act 30 minutes after injection, reaches its peak at 2 - 4 hours, and lasts about 6 hours. Regular insulin may be administered before a meal and may be better for high-fat meals.
Intermediate Insulin. NPH (neutral protamine Hagedorn) insulin has been the standard intermediate form. It works within 2 - 4 hours, peaks 4 - 12 hours later, and lasts up to 18 hours. Lente (insulin zinc) is another intermediate insulin that peaks 4 - 12 hours and lasts up to 18 hours.
Long-Acting (Ultralente) Insulin. Long-acting insulins, such as insulin glargine (Lantus), are released slowly. Insulin glargine matches parts of natural insulin and maintains stable activity for more than 24 hours. Studies suggest that it poses less of a risk for hypoglycemia and weight gain than NPH. It has a higher incidence of pain at the injection site than NPH. Ultralente insulin peaks at 10 hours and lasts up to 20 hours but varies greatly in activity from day to day.
Combinations. Regimens generally include combinations of short and longer-acting insulins to help match the natural cycle. For example, one approach in patients who are intensively controlling their glucose levels uses 3 injections of insulin, which includes a mixture of regular insulin and NPH at dinner. Another approach uses 4 injections, including a separate short-acting form at dinner and NPH at bedtime, which may pose a lower risk for nighttime hypoglycemia than the 3-injection regimen.
Insulin Pens. Insulin pens, which contain cartridges of insulin, have been available for some time. Until recently, they were fairly complicated and difficult to use. Newer, prefilled pens (Humulin Pen, Humalog) are disposable and allow the patient to dial in the correct amount.
Insulin Pumps. An insulin pump can improve blood glucose control and quality of life with fewer hypoglycemic episodes than multiple injections. The pumps correct for the “dawn phenomenon” (sudden rise of blood glucose in the morning) and allow quick reductions for specific situations, such as exercise. Many different brands are available.
The typical pump is about the size of a beeper and has a digital display. Some are worn externally and are programmed to deliver insulin through a catheter in the skin or the abdomen. They generally use rapid-acting insulin, the most predictable type. They work by administering a small amount of insulin continuously (the basal rate) and a higher dose (a bolus dose) when food is eaten.
Many adults, adolescents, and school children use insulin pumps. Studies indicate that even very young children (ages 2 - 7 years) can successfully use insulin pumps and that the pumps may help improve blood sugar control.
Learning to use the pump can be complicated, although over time most patients find the devices are fairly easy to use. To achieve good control, patients and parents of children must undergo some training. The patient and doctor must determine the amount of insulin used -- it is not automatically calculated. This requires an initial learning period, including understanding insulin needs over the course of the day and in different situations and knowledge of carbohydrate counting. Frequent blood testing is very important, particularly during the training period.
Insulin pumps are more expensive than insulin shots and occasionally have some complications, such as blockage in the device or skin irritation at the infusion site. In spite of early reports of a higher risk for ketoacidosis with pumps, more recent studies have found no higher risk.
Pramlintide (Symlin) is a new type of injectable drug that can help control postprandial hyperglycemia, the sudden increase in blood sugar after a meal. Pramlintide is injected before meals and can help lower blood sugar levels in the 3 hours after meals. Pramlintide is used in addition to insulin for patients who take insulin regularly but still need better blood sugar control. The FDA approved this drug in 2005 for adults with type 1 and type 2 diabetes. Pramlintide and insulin are the only two drugs approved for treatment of type 1 diabetes.
Pramlintide is a synthetic form of amylin, a hormone that is related to insulin. Side effects may include nausea, vomiting, abdominal pain, headache, fatigue, and dizziness. Patients with type 1 diabetes have an increased risk of severe low blood sugar (hypoglycemia) that may occur within 3 hours following a pramlintide injection. This drug should not be used if patients have trouble knowing when their blood sugar is low or have slow stomach emptying (gastroparesis).
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