Some bodybuilders take insulin as an adjunct to training, citing several reasons: 1.) Insulin stimulates glycogen synthesis; 2.) Insulin
promotes amino-acid entry into muscle, thus promoting a pronounced anabolic effect; 3.) Insulin counters the blood- glucose-raising effects
of growth hormone; and 4.) Insulin may make growth hormone more effective.
Unfortunately, the optimal dosage of insulin needed for these purposes is unknown. In addition, insulin use is fraught with dangers, such as a swift lowering of blood glucose, which could induce a coma. Insulin is also a potent water-retaining and fat-promoting hormone.
The negative health effects of insulin in non-diabetics were shown in a recent Japanese study that examined the effects of hyperinsulinemia (high blood-insulin levels) in a non-diabetic population. The study involved 147 males with normal glucose tolerance who took a 75-gram glucose-load drink to stimulate hyperinsulinemia.
Results showed that increased insulin release led to higher blood fats, decreased oxygen delivery to muscles during exercise, increased bodyfat deposition and decreased high density lipoprotein levels. (High-density lipoproteins protect against cardiovascular disease.) When the subjects of the Japanese study reduced their weight, most of the negative effects dissipated.
Considering that anabolic steroids induce many of these same effects, the concomitant use of steroids with insulin dangerously increases the health risks.