TRH-induced growth hormone release in insulin-dependent diabetes mellitus

Growth hormone (GH) response was studied in 8 insulin-dependent and 7 non-insulin-dependent diabetics after stimulation with L-Dopa (500 mg orally) and TRH (0.2 mg iv.). L-Dopa induced a clear GH response in insulin-dependent diabetes (IDDM) and in the control group while in non-insulin-dependent diabetes (NIDDM) peak GH levels were lower (P less than 0.05) and 4 of 7 subjects failed to respond to L-Dopa stimulation. TRH had no effect on GH levels in NIDDM and in the controls. Insulin-dependent diabetics responded to TRH stimulation and GH levels at 20 and 30 min were significantly higher as compared with NIDDM and the control group. The degree of hyperglycemia seemed not to influence GH response. The highest GH levels were noted in two patients with proliferative retinopathy. It is suggested that TRH-induced GH release may be a characteristic feature in some patients with IDDM.