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.

 

Concentration Strength

 

     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.

 

Source

 

     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

otherwise.

 

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

chart!"

 

     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

pre mix.   

 

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

gospel.

 

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

be consequences.

 

A Caution

 

     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.

 

Adjusting Insulin

 

     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

power!

 

     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

control!

 

     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.