1. Short acting insulin
I. Soluble insulin
II. Rapid acting insulin analogues
2. Intermediate acting insulin
3. Long acting insulin
4. Mixed insulin
Soluble insulin is a short acting insulin. This is the most appropriate form of insulin for use in diabetic emergencies and at the time of surgery. There are two types of soluble insulins;
1. Soluble human insulin (Product of DNA recombinant technique)
2. Soluble animal insulin (Bovine and porcine)
Soluble insulin is injected 15-30 minutes prior to a meal. It reaches peak concentration within 60-90 minutes and duration of action is about 8 hours. It can be administrate in intravenous, intramuscular and subcutaneous routes.
Rapid acting insulin analogue
The structure of the insulin molecule is modified as to change its pharmacokinetics without altering the biological effects
The human insulin analogues have a faster onset and shorter duration of action; as a result, compared to soluble insulin, fasting and pre-prandial blood glucose concentration is a little lower, and hypoglycemia occurs slightly less likely. Route of administration is subcutaneous. There are two types of analogues available;
1. Insulin lispro
2. Insulin aspart
Intermediate acting insulin
When they are given in subcutaneous route, the onset of action is 1-2 hours and duration of action is about 18-24 hours. There are two types of intermediate acting insulin;
1. Isophane insulin (NPH: Neutral Protamine Hagedorn);
This is prepared by adding protamine into soluble insulin. It has a cloudy appearance. This can be pre-mixed with soluble insulin or can be combined with insulin analogues as well
2. Insulin Zn suspension (Crystalline/ lente insulin);
Prepared by adding Zn into soluble insulin
Duration of action is longer than that of NPH
Cannot be pre-mixed with soluble insulin, but can be mixed just prior to inject.
Long acting insulin
Onset of action is 4-6 hours and duration of action is 24-36 hours when given subcutaneously. There are mainly two types;
1. Insulin gargling
This is an insulin analogue. It has a prolonged duration of action and it is given once a daily basis.
2. Protamine Zn insulin (ultralente)
Given once a daily basis
Usually given with soluble insulin
This is the commonest way of giving insulin. Preparations are made to suit the patients’ need. There are several preparations available;
1. Biphasic insulin aspart
This is the mixture of insulin aspart(30%) and isophane insulin(70%).
2. Biphasic insulin lispro
This is the mixture of insulin lispro and isophane insulin. Percentages can be varying.
Eg; Biphasic insulin lispro 25 (25% insulin lispro and 75% isophane insulin)
Biphasic insulin lispro 50 (50% insulin lispro and 50% isophane insulin)
3. Biphasic isophane insulin
This is the mixture of soluble insulin and isophane insulin. Percentages can be varying.
Eg; Biphasic isophane insulin30/70(30% soluble insulin and 70% isophane insulin)
Biphasic isophane insulin10 (10% soluble insulin and 90% isophane insulin)
Biphasic isophane insulin20 (20% soluble insulin and 80% isophane insulin)
Biphasic isophane insulin40 (40% soluble insulin and 60% isophane insulin)