Human Insulin

Synthetic human insulin is identical in structure to your own natural insulin. But when it is injected under the skin it doesn’t work as well as natural insulin. This is because injected human insulin clumps together and takes a long time to get absorbed. The activity of this synthetic human insulin is not as well synchronized with your body’s needs.

In this section, you will find information about:

Fast-acting injected insulin

Relative to the rapid-acting insulin analogs, Regular human insulin has different features, such as a delayed onset of action, and variable peak and duration of action when it is injected under the skin. Because of this, fewer and fewer medical providers are prescribing Regular insulin. The delayed onset of action is the reason you have to inject the insulin and wait before eating.  The longer and dose dependent duration of action may predispose you to low blood glucose levels long after the meal is over.

Rapid Acting Insulin Analogs - Advantages for Mealtime/Bolus Coverage chart

REGULAR INSULIN IS LESS PREDICTABLE THAN RAPID-ACTING ANALOG VERSIONS when injected under the skin.

Regular Human Insulin Peak Time : 2-4 Hours

Intermediate-acting insulin:

NPH (Neutral Protamine Hagedorn) is a longer-acting human insulin that is used to cover blood glucose between meals, and to satisfy your overnight insulin requirement. A fish protein, protamine, has been added to the Regular human insulin to delay its absorption. This long acting insulin is a cloudy suspension that needs to be remixed thoroughly before each injection. Because NPH is a suspension of different sized crystals, it has a more unpredictable absorption rate and action.  The use of NPH has declined with the availability of other long-acting insulin options, specifically, the long-acting insulin analogs, insulins glargine, degludec and detemir.  NPH has an onset of insulin effect of 1 to 2 hours, a peak effect of 4 to 6 hours, and duration of action of more than 12 hours. Very small doses will have an earlier peak effect and shorter duration of action, while higher doses will have a longer time to peak effect and prolonged duration.

Long Acting Insulin Analog - Advantages for Basal Coverage Chart

Additional information about NPH:

  • An optimal NPH regimen involves small doses before meals (for between-meal insulin coverage), with a larger dose at bedtime (to cover this longer time period). In this regimen, rapid acting insulin analogs need to be given at mealtime or for high glucose correction (ie as bolus therapy).
  • The traditional NPH insulin regimens use two injections of NPH per day. The first dose covers the day and the second dose covers the evening and night. With this basic regimen, Regular insulin also is given before breakfast and dinner.
  • An alternative NPH regimen is to give Regular insulin alone at meals and NPH at bedtime.
  • Other regimens use various combinations of rapid-acting analog insulin or Regular insulin and NPH.