The effect of pirenzepine on growth hormone and blood glucose levels in Type I diabetes mellitus

: Increased GH levels in Type I diabetes mellitus have been implicated in the pathogenesis of metabolic complications such as the so-called dawn phenomenon. GH secretion is under control of cholinergic mechanisms. In 21 Type I diabetic patients the effect of oral administration of the anticholinergic drug pirenzepine in addition to intensive insulin therapy on GH and blood glucose levels was studied. At 21.30, 08.00 and 12.00 h, all patients received in random order 50 mg of pirenzepine or placebo po. Blood for determination of GH, blood glucose, cortisol and C-peptide levels were obtained at 3-h intervals. Serum levels of plasma glucose and GH were significantly lower under pirenzepine than under placebo (P less than 0.05 and P less than 0.01, respectively). Serum levels of cortisol, free insulin and C-peptide were comparable on the test and the control day. Our data indicate that in Type I diabetes mellitus the anticholinergic drug pirenzepine is effective in decreasing both GH and blood glucose levels.