Insulins are categorized first by length of action.
1. Rapid-Fast acting Insulin: begins to work approximately ❌ min after injection, peaks in about 1 hour, and continues to work for 2 to 4 hour.
This is usually taken directly prior to a ❌ and in addition to a ❌-acting insulin.
2. Short-Regular acting Insulin: reaches the bloodstream ❌min to an hour after injection, peaks anywhere from 2 to 3 hours after Injection, and is effective for approximately 6-8 hours.
It is usually given before a meal and in addition to a long-acting
insulin.
3. Intermediate acting Insulin: generally reaches the bloodstream about ❌ hours after injection, peaks 4 to 8 hours later and is effective for about 12 to 18 hours.
It is usually taken ❌ a day and in addition to a ❌ acting insulin.
4. Long acting Insulin: starts working several hours after injection and works for approximately ❌ hours.
If necessary, it is often used in combination with rapid- or short acting insulin.

Rapid insulins are lispro, aspart, and glulisine.
• Lispro - a human analogue which works ❌ quickly than soluble human insulin because the insulin molecule has been changed slightly. Through ❌ DNA technology, the final lysine and proline residues on the C-terminal end of the ❌-chain are reversed. This modification does not alter receptor binding, but blocks the re-formation of insulin ❌. It is sold under the brand name ❌.
• Aspart - a human analogue which also works ❌ than soluble human insulin because of a substitution which reduces the tendency of the
insulin to form ❌. Sold under the brand name ❌.

Insulin glargine, marketed under the brand name ❌, is a human insulin analogue. After injection, micro-❌ slowly release insulin for about 24
hours. It uses pH reactions to form micro-precipitates under the skin,
which create the time-release action.
Insulin glargine differs from human insulin by replacing asparagine with
❌ in position 21 of the ❌-chain, and by carboxy-terminal extension of
❌-chain by 2 ❌ residues. The arginine amino acids shift the isoelectric point from a pH of 5.4 to 6.7, making the molecule more soluble at an ❌ pH and less soluble at ❌ pH.
This allows for the subcutaneous injection of a ❌ solution with ❌ dissolution and absorption for at least 24 hours.