Insulin induced hypoglycemia for testing of growth hormone (GH) release is not routinely used by the majority of endocrinologists and concern remains regarding its safety. Severe side effects have been reported. Because of this, we have reviewed our experience which includes 56 patients from the academic center and 41 from a private practice. The results in the two settings were similar and are combined. No severe reactions were observed. Symptoms, including some combination of sleepiness, restlessness, hunger, diaphoresis, tachycardia and palpitations, were recorded in 45%. No significant correlation of symptoms with blood glucose whether nadir 31.7 mgm/dl symptomatic (S) vs. 33.2 mgm/dl non-symptomatic (N), mean 55.8 (S) vs. 61.7 (N), or decline 45.6(S) vs. 51.3 (N) was found. No relationship of symptoms to cortisol or growth hormone responses was found.

Of patients, 91% had previously failed to achieve GH concentration of 10 ng/ml in response to clonidine. Only 4 responded to insulin with a GH concentration of > 10 ng/ml. There was not a significant correlation of results of the two stimulation tests.

We conclude that 1) carefully performed the insulin test is not accompanied by severe reactions 2) symptoms do not correlate well with hormonal responses 3) clonidine stimulation provides a good test of GH release as reflected in the results of the insulin stimulation test.