No human being can go more than a few days at most without insulin. Insulin controls blood sugar levels by taking the excess from the blood and ordering it "into storage" as ready-releasable compounds like glycogen. Glycogen is stored in the liver, but also around muscle tissue, in preparation for required sudden release, e.g. in a "flight from predators" response, or more likely, in a bout of vigorous exercise. The requirement for insulin of athletes such as Geoff Capes and Stephen Redgrave is the same as any of us, but unfortunately, as they have Type I Diabetes, they cannot produce their own, and therefore need to inject insulin every day (normally at every mealtime).
Insulin, as with other peptide hormones, is increasingly abused by elite athletes willing to compromise their integrity. A large black market in illegal sales and use of insulin now exists, particularly on the body-building circuit. A recent scandal highlighted in the news is the abuse of insulin by the Italian cyclist Marco Pantani, who certainly appears to be unstoppable….in what lengths he will take to win at least! Community pharmacists in Limerick, Cork, Dublin and more so in the UK frequently come across incidences of used insulin vials and syringes changing hands from £1.00 to £10 in the UK ( 1.5 to 15 Euro) per unit; penfills are averaging about £60 stg.
Without giving enough information to encourage misuse, the advantage of Insulin (as well as some other human hormone analogues) to the cheat is that it is almost impossible to tell apart from the naturally occurring form, plus it has a very short half-life, meaning it clears the body very rapidly. Insulin is only really anabolic in the presence of other substances, and during or just before exercise, and so the ill-informed may be putting themselves at risk without gaining any advantage.
First, insulin rapidly lowers blood sugar, and this leads to lower oxygen levels (not to mention calcium, potassium and many other minerals. Low oxygen will irreversibly damage brain, liver and kidney cells. Often the first indication of this is collapse, coma, or a seizure (epileptic type fit) and ultimately the risk can be fatal.
Second is the obvious risk is shared needles. If they are buying pre-filled insulin syringes, these normally have an attached needle, if the patient has an infection of a transmissible kind, this will be injected into the abuser.
Third, an allergic reaction to the artificial insulin would not be detected due to the "athlete" not being a registered diabetic.
Surely no victory can be worth risking life. Athletes who abuse insulin are playing a very deadly game.
To touch on more complicated biochemistry more insulin needs more sugar to burn. If it doesn't get sugar, it will burn protein, and all of these produce by-products like ketones, lactic acid, and other toxic metabolites. If enough fluids are not consumed, or if the kidneys or liver are less than fully healthy, these compounds could do untold damage to the body.
In short, as with any abuse, insulin cheating is high risk. Pantani's name has now been reduced to the deplorable, and the recent revelations fulfill the often-offered theory that if an apparently diminutive body is producing almost super-human output, that body must be either (a) physiologically or (b) pharmacologically adapted. In some sad cases the evidence is overwhelming.
FOOTNOTE: in a more encouraging development, theathlete.org have learned at a recent doping educational seminar that a unique identifier test for GROWTH-HORMONES is inevitable. Articles on this and other developments such as hair-tests to follow soon….