INSULIN TYPES: A REVIEW
Earlier articles have discussed insulin's role in our
bodies, what happens when we don't have it, and why some of
us have to take it by injection. But all insulins are not
the same. How are they different? WHY are they different?
And, how can we use their differences to better self manage?
Insulins are described and subdivided by concentration
strength, source, and time of onset/peak. This last
category is most critical, but we really need an
understanding of all three criteria.
All insulins sold in the United States today are of
U 100 strength, 100 units of insulin per cc of fluid. But
there are other dilutions in other countries, and if you
were to encounter one of these (all perfectly usable), and
inject your usual volume of insulin, you'd get a different
amount of insulin. You'd get the wrong dosage.
At one time, all insulin was produced by laboratory
animals, most often cows and pigs. In the last decade,
however, American insulin manufacturers have almost
completely shifted to use of "recombinant DNA" (Rdna)
technology, enabling laboratory production of a close analog
to real human insulin. This "human" insulin is said to more
closely match our endogenous (pancreatic) insulin.
Although labelled much like "animal source" insulins,
recombinant DNA insulins are not quite the same, either in
time of onset or in amount of insulin required. Experience
shows that any switch between the one and the other must be
done with care, and under your doctor's supervision the
types might be different enough to cause you trouble
Time of Onset/Peak
The different insulin types: "Humalog, Regular, NPH,
Lente, Ultralente, Lantus", and the pre mixes: 70/30, 50/50,
and Humalog 75/25, are divided and distinguished by their
time of onset and duration. As shown in the chart below,
critical questions are:
1. When does this insulin begin to act in my body?
2. When does it reach its peak?
3. When does it fade to insignificance?
NOTE: " We're all different! Charts reflect
averages you may well find a given insulin is different for
you. Test frequently, keep good notes, and make your own
The chart below is a general approximation, derived
from data furnished by all three U.S. insulin manufacturers,
Eli Lilly and Company, Aventis Pharmaceuticals, and Novo
Nordisk Pharmaceuticals Inc.
INSULIN START PEAK END
Humalog 10 min. 1 hr. 4 hr.
Regular 30 min. 2 5 hr. 8 hr.
NPH 1.5 hr. 4 12 hr. 22 hr.
Lente 2.5 hr. 6 16 hr. 24 hr.
Ultralente 4 hr. 8 18 hr. 30 hr.
Lantus 1.5 hr. 2‑23 hr 24 hr
70/30 2 hr. 2 12 hr. 24 hr.
50/50 2 hr. 2 6 hr. 24 hr.
Humalog 75/25 15 min. 1 6.5 hr. 18/26 hr.
Where Humalog, Regular, and 50/50 premix have sharp and
definable "peaks," the long acting Lente insulins come on
slowly, and have long, flat "peaks," and a slow rate of
decline. New Lantus insulin (insulin glargine Rdna) is even
flatter, and is meant, like the Lente insulins, to provide
"basal" insulin coverage. Discuss your insulin choices
with your doctor and your diabetes educator they will help
you find which is best for you.
There are a number of insulins not charted above. Some
are "buffered insulins" (from both Lilly and Novo Nordisk),
and there is a special U 400 insulin from Aventis. These
are strictly for use in insulin pumps, and should not be
used for any other purpose! There are also insulins not
available in the United States (or not yet available), such
as the complete line of Hypurin animal source insulins
manufactured by CP Pharmaceuticals of Great Britain, Novo
Nordisk's rapid acting Novolog, or Lilly's 50/50 Humalog
Avoid Rigid Thinking
The most accurate chart will still be imprecise.
Short term, things will vary because diabetes, like life
itself, is like riding a surfboard no one can control all
factors! Novo Nordisk says it best, on their chart: "The
time course of action of any insulin may vary in different
individuals, or at different times in the same individual.
Because of this variation, time periods indicated here
should be considered as general guidelines only."
Long term, things will vary because your body is not
the same from one decade, or one year, to the next. Your
chart will need regular updating. Use it as guide, not
Mixes and Mixing
Although users of the insulin pump generally take only
short acting insulin, most insulin using diabetics employ a
mix of faster and slower insulins, to provide best control.
The idea is to let the fast insulins (Regular or Humalog)
cover meals, and let the longer acting types (NPH, Lente,
Ultralente) cover the period between meals. There is quite
an art to insulin mixing, as you must consider diet,
exercise, injection frequency, total insulin volume, ratio
of slow to fast insulins, general health (including other
medications you might be taking!), and your own unique
intangibles. NOBODY is exactly "average."
Some folks employ commercially prepared "pre mixes,"
like "70/30" (70% NPH to 30% R). While these pre mixed
insulins provide a convenience (precise and consistent
mixing) they also come with a liability: What if, to
achieve optimal control, your best mix, right now, is 68/32,
or 75/25? And what if tomorrow, due to variations in your
diet, activity level, and general health, it's 60/40 or
81/19? You can't make fine adjustments with a "pre mixed
insulin" you're stuck with the mix the doctor gave you and
for some, that means less than optimal control. Yes, you
can vary your total dosage, total volume, and injection
frequency; but, as the different insulins are really there
for different purposes, adjusting insulin with a pre‑mix can
be like scratching an itch with a sledgehammer. There can
The insulin manufacturers report that one insulin mix
could have dangerous consequences, and should be avoided.
The Lente insulins, long acting insulins, should never be
combined with intermediate speed NPH insulin. Chemicals in
the NPH would alter the Lente or Ultralente, turning it into
an approximation of fast acting Regular insulin! Mix those
two, and you'll have a very different result than you might
expect! Also, notes supplied with new Lantus insulin state:
"Lantus must not be diluted or mixed with any other insulin
or solution, as it may result in a delayed onset of action."
Be sure to talk to your doctor about appropriate and
inappropriate insulin combinations.
People's bodies, and their insulin needs, change. Not
only by the year, the month, or the decade, but, to achieve
the best possible control, you may choose to vary your
dosages by day, linking them to results of your blood
glucose monitoring. To preserve optimal control, you will
need to adjust your insulins, to compute, draw up, and
inject different amounts and mixture percentages. Some
folks, working with the full potential of "tight control,"
use a "sliding scale", adjusting their insulins every day,
in close step with their diet, exercise, and blood glucose
test results. The rewards of their discipline greatly
reduced chance of complications can be great.
Once you realize the role played by the different types
of insulin, and how you can optimize your control by
utilizing the most appropriate blend, right here, right now,
you're well on the road to staying healthy. Knowledge is
Blind diabetics, and those losing vision, need to
adjust insulin as well, and the technology to do so is
available: Tactile insulin measuring devices like the
Jordan Count A Dose enable reliable non visual insulin
measurement and mixing. Lack of sight is no bar to good
The Count‑A Dose (Low Dose model, B D 50 unit syringe)
from Jordan Medical Enterprises (of South Pasadena, CA), is
available from the National Federation of the Blind,
Materials Center, 1800 Johnson Street, Baltimore, MD 21230;
telephone: (410) 659 9314. Cost is $40. The Materials
Center is open 8:00 am to 5:00 pm EST, weekdays.