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���������������� 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. |
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