Insulin is needed to help the body use or store the sugar or glucose it gets from foods. The pancreas can no longer make insulin in people who have Type I diabetes, so they must rely on insulin injections. According to the Mayo Clinic, there are several types of insulin available, and they vary in how quickly they work and how long they last in the body.
The hypoglycemic effect refers to the peak onset of an insulin or when it is more apt to cause hypoglycemia or a low blood sugar. Familydoctor.org explains that when insulin is used, the blood sugar level can get too low if the diabetic does not eat enough or on time, if he takes too much insulin or if she exercises more than usual.
Rapid Acting Insulin
Rapid acting insulin is absorbed more quickly than any other insulin, but the effect wears off the soonest, according to Mayoclinic.com. Brand names of rapid acting insulins are Novolog, Apidra and Humalog. This insulin type begins working in 15 minutes, and the peak hypoglycemic effect is 30 minutes to three hours after injection. The duration of rapid acting insulin is from two to five hours. This insulin should be injected no more than 15 minutes before eating, per Familydoctor.org. The American Academy of Family Physicians says that Humalog, or insulin Lispro is the first commercially available insulin analog. This type leads to lessened hypoglycemic events due to the way it is absorbed in the body, as long as the patient eats within 15 minutes of injection.
Short Acting Insulin
Short acting insulin, also called regular human insulin, works quickly, but the effects don't last as long as intermediate acting insulin, states the Mayo Clinic. Brand names include Humulin R and Novolin R. This insulin begins working in 30 to 60 minutes, with the peak hypoglycemic effect occuring in two to four hours. The length of this type of insulin's effect is three to eight hours. The American Academy of Family Physicians states that short acting insulin seldom achieves glycemic control because it contains hexamers of insulin crystallized around a zinc molecule. This limits insulin absorption, as it must dissociate, then diffuse before being absorbed into the blood stream. The AAFP states that this predisposes patients to hypoglycemia, as this regular insulin is still present in the blood when the peripheral glucose disposal occurs up to 90 minutes later.
Intermediate Acting Insulin
The Mayo Clinic describes intermediate acting insulin as one that starts working later than short acting insulin, but the effects last longer. Brand names consist of Humulin N and Novolin N. The onset of action is between one and four hours and the peak hypoglycemic effect occurs anywhere between four to 12 hours. Intermediate acting insulin can last a duration of 12 to 18 hours. The "British Medical Journal" published a report in 1983 that studied the effect of delaying the evening injection of intermediate acting insulin by four and a half hours. They found that this delayed the lowest point in blood glucose levels during the night, and reduced the fasting and peak levels after breakfast in diabetic patients. The Mayo Clinic explains that in some cases, a combination of intermediate acting and short or rapid acting insulin in one bottle may be an option, to balance the peak hypoglycemic effects.
Long Acting Insulin
The long acting insulin takes several hours to work, but provides insulin at a steady level for up to 24 hours. Brand names include Lantus and Levemir. The onset of action can occur from one to 10 hours; there is no clear hypoglycemic peak with this insulin type. The duration effect can last for up to 24 hours. A study reported in the "Cochrane Database of Systemic Reviews" found that long acting insulin caused slightly less hypoglycemic events than did intermediate acting insulin. They concluded that long acting preparations seem to exert a beneficial effect on night time glucose levels.
