This evidence convinced most physicians who specialize in diabetes care that an important goal of treatment is to make the biochemical profile of the diabetic patient (blood lipids, HbA1c, etc.) as close to the values of non-diabetic people as possible. This is especially true for young patients with many decades of life ahead.
Most insulin used each day is produced during the digestion of meals. Insulin levels rise immediately as we begin to eat, remaining higher than the basal rate for 1 to 4 hours. This meal-associated (prandial) insulin production is roughly proportional to the amount of carbohydrate in the meal.
Intensive or flexible therapy involves supplying a continual supply of insulin to serve as the basal insulin, supplying meal insulin in doses proportional to nutritional load of the meals, and supplying extra insulin when needed to correct high glucose levels. These three components of the insulin regimen are commonly referred to as basal insulin, meal insulin, and high correction.
In an MDI regimen, long-acting insulins are preferred for basal use. An older insulin used for this purpose is ultralente. Levemir, made by Novo Nordisk, is another long-acting insulin in trials. Also insulin glargine (brandname: Lantus, made by Aventis) is used. Rapid-acting insulin analogs such as lispro (brandname: Humalog, made by Eli Lilly and Company) and aspart (brandname: Novolog/Novorapid, made by Novo) are preferred over older regular insulin for meal coverage and high correction. Many people on MDI regimens carry insulin pens to inject their rapid-acting insulins instead of traditional syringes. Some people on an MDI regimen also use injection ports such as the I-port to minimize the number of daily skin punctures.
The other method of intensive/flexible insulin therapy is an insulin pump. It is a small mechanical device about the size of a deck of cards. It contains a syringe-like reservoir with about three days' insulin supply. This is connected by thin, disposable, plastic tubing to a needle-like cannula inserted into the patient's skin and held in place by an adhesive patch. The infusion tubing and cannula must be removed and replaced every few days.
An insulin pump can be programmed to infuse a steady amount of rapid-acting insulin under the skin. This steady infusion is termed the basal rate and is designed to supply the background insulin needs. Each time the patient eats, he or she must press a button on the pump to deliver a specified dose of insulin to cover that meal. Extra insulin is also given the same way to correct a high glucose reading. Current pumps do not include a glucose sensor and cannot automatically respond to meals or to rising or falling glucose levels.
Both MDI and pumping can achieve similarly excellent glycemic control. Some people prefer injections because they are less expensive than pumps and do not require the wearing of a continually attached device. A primary advantage of pumps is the freedom from syringes and injections.
Intensive/flexible insulin therapy requires frequent blood glucose checking. To achieve the best balance of blood sugar with either intensive/flexible method, a patient must check his or her glucose level with a meter monitoring of blood glucose several times a day. This allows optimization of the basal insulin and meal coverage as well as correction of high glucose episodes.
Major disadvantages of intensive/flexible therapy are that it requires greater amounts of education and effort to achieve the goals, and it substantially increases the daily cost of diabetes care.
It is a common misconception that more frequent hypoglycemia is a disadvantage of intensive/flexible regimens. The frequency of hypoglycemia increases with increasing effort to achieve normal blood glucoses with any insulin regimen. When traditional regimens are used aggressively enough to achieve near-normal glycosylated hemoglobin A1c levels, hypoglycemia is at least as frequent as with flexible regimens. When used correctly, flexible regimens offer greater ability to achieve good glycemic control with easier accommodation to variations of eating and physical activity.
The insulin pump is the device used in intensive insulinotherapy. The insulin pump is about the size of a beeper. It can be programmed to send a steady stream of insulin as basal insulin. It contains a reservoir or cartridge holding several days' worth of insulin, the tiny battery-operated pump, and the computer chip that regulates how much insulin is pumped. The infusion set is a thin plastic tube with a fine needle at the end. It carries the insulin from the pump to the infusion site beneath the skin. It sends a larger amount before eating meals as "bolus" doses.
The insulin pump replaces insulin injections. This device is useful for people who regularly forget to inject themselves or for people who don’t like injections. This machine does the injecting by replacing the slow-acting insulin for basal needs with an on-going infusion of rapid-acting insulin.
Basal Insulin: the insulin that controls blood glucose levels between meals and overnight. It controls glucose in the fasting state.
Boluses: the insulin that is released when food is eaten or to correct a high reading.