One of the most frequently asked questions I receive is: "Do I really need to be on insulin?"  Well, if you have Type 1 diabetes (click here for a discussion on the differences between Type 1 and Type 2 diabetes) then unless you take insulin you will not survive.  If you have Type 2 diabetes, insulin is usually reserved for the situation wherein lifestyle measures (proper diet, exercise, getting to a good weight, etc.) and oral hypoglycemic agents are not sufficient to maintain adequate blood glucose control.  Regardless of which type of diabetes you have, the goal is to have optimal sugar control because the better your sugars are, the lower is the likelihood of progressive damage to your body (especially your eyes, your kidneys and your nerve endings).  If you are interested, you can refer to the two landmark studies that confirmed this: the DCCT study for DM 1 & the UKPDS for DM 2. 

Once the decision is made that insulin is necessary then it must be decided which type of insulin is to be used and how often it is to be given.

In tabular format the available insulins in Canada are:

(* Regular insulin is referred to as 'Toronto' insulin everywhere in the world so long as your world happens to be confined to a town of about two million people located on the northwestern shore of Lake Ontario where insulin was first discovered.)

The actions of these insulins are shown on this graph (Apidra is not yet available in Canada):

(Adapted from NEJM, 352;2 and other sources)

It is very important to know that the properties noted above are averages and there can be quite a bit of difference in how you respond to a type of insulin compared with how someone else responds to that same insulin; heck, even for how you respond on one occasion compared to another!  See here for more on insulin action variability).

For individuals with Type 1 diabetes (and for many people with type 2 diabetes), far and away the preferred insulin regimen is to be on "intensified" management.  This is usually best accomplished  with a rapid-acting insulin (Humalog or Novorapid) given with meals and a longer acting insulin (NPH or Lantus or Levemir) given at bedtime.  Some people will require the longer acting insulin to be given twice a day (breakfast and bedtime).

Compared with regular insulin, rapid-acting insulin has the advantage of being faster acting and hence is given just as you are about to eat whereas regular insulin should be given about 1/2 hour before you eat (though virtually no one does).  Additionally, rapid-acting insulin peaks quickly and leaves the body quickly so it helps to bring the sugar level down faster after you eat.  Also, since it leaves the system quickly it makes insulin reactions less likely to occur several hours after the insulin dose is given.  And most (but not all) people on Humalog or Novorapid find it more flexible in terms of meal timing and dose adjustment based on size/type of meals and exercise.  Having said all that, if you are on regular insulin with your meals and are doing just fine with that, then there is no compelling reason to switch to Humalog or NovoRapid.

Lantus (glargine) and Levemir (detemir) are longer acting insulins than NPH and tend to give more consistent control with fewer episodes of hypoglycemia (especially overnight).  I've used these newer insulins with increasing frequency in my practice and to this point have been thrilled with the results.  One important caveat though: they are much more expensive than NPH.

The following table illustrates the usual insulin schedule for people on NPH & Humalog (or NovoRapid):

* (An additional dose of NPH insulin given in the morning is often necessary for people with type 1 diabetes.)

The following table illustrates the usual insulin schedule for people on Lantus (or Levemir) & Humalog (or NovoRapid):

*(Lantus is usually initiated at bedtime, but for most people it works equally well if given at any time of day...it's important, though, to be consistent day-to-day in terms of when you give it.  Also, whereas Lantus is almost always given once a day, Levemir insulin is often needed twice a day if you have type 1 diabetes.)

The following table illustrates the usual insulin schedule for people on NPH & regular insulin:

So what schedule should you be on?  The answer is simple.  Whatever works best for you.  Often this is determined only by trial and error.  I talk about how to adjust insulin on the Frequently Asked Questions page.

The other choice available for intensive insulin management is insulin pump therapy.  I discuss this option further here.

For individuals with Type 2 diabetes, when insulin is needed it has typically been given as a pre-mixed combination of regular and NPH insulin (generally in a ratio of 1/3 regular and 2/3 NPH) with a larger dose in the morning and a smaller dose in the evening, however intensified insulin therapy (described above) is gradually taking over as the preferred insulin strategy for those people with type 2 diabetes who require insulin (due to its greater flexibility and, often, its better ability to achieve target blood glucose readings).  As Type 2 diabetes is a condition of insulin resistance, it is increasingly common to be on both insulin (given to make up for the pancreas' shortfall in insulin production) and oral hypoglycemic agents (particularly metformin) to allow the insulin to work more effectively.  TZD drugs (egs., Avandia, Actos) also work well in this circumstance, but are not "officially approved" (in Canada anyhow) for this indication and increase the risk of congestive heart failure; as such, if a TZD and insulin are used together this needs to be done with great care.

Regardless of which insulin schedule is used, it is crucial to think of starting insulin as just that - a start - with the dose often intentionally an underestimate of what your requirements are likely to be with the expectation being that frequent dose adjustment will be necessary (done under the close supervision of a physician and/or a diabetes nurse educator) until target readings are reached.  Simply put, it is safer to under-dose someone with insulin than to over-dose them.  A motto a wise doctor follows when starting a patient on insulin: "start low & go slow."  (Though, I should add, not too slow!).  You might wish to have a look at a copy of a letter I give out to my patients who are being started on insulin.