The effect of selective beta 1-blockade on glucose thresholds for release of counterregulatory hormones and symptoms in insulin-dependent diabetes mellitus.
To evaluate the effect of beta 1-blockade (metoprolol) on the plasma glucose thresholds initiating counterregulatory hormone responses and symptoms of hypoglycemia, we used a modified glucose clamp technique to produce a standardized gradual glucose decline from 5.0 to 2.0 mmol/l in nine patients with insulin-dependent diabetes mellitus (IDDM) (HbAlc range 6.7-10.3%, duration of diabetes 5-18 years, autonomous neuropathy present in three of the patients). The responses were studied once with metoprolol and once with placebo, in random order. With the beta 1-selective blockade, epinephrine release was triggered at a significantly higher (p less than 0.02) plasma glucose level (3.5 mmol/l) than it was with placebo (3.0 mmol/l). Metoprolol did not change thresholds for growth hormone (3.7/3.5 mmol/l), cortisol (2.9/2.9 mmol/l), glucagon (2.8/2.8 mmol/l) or for pancreatic polypeptide (2.8/2.7 mmol/l). The peak responses of epinephrine and growth hormone were significantly higher (p less than 0.01) with the beta 1-blockade. Metoprolol did not change the thresholds for neuroglycopenic and autonomic symptoms. Six out of the seven patients who answered yes to having hypoglycemia did so at a higher blood glucose with metoprolol than without. In our study, the beta 1-selective blockade altered the responses of counterregulatory hormones, but it did not change the thresholds for hypoglycemic symptoms.
Institute of Clinical Medicine, University of Tromsø, Norway.
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D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D001794:Blood Pressure; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000503:physiopathology*; D004056:Differential Threshold; D006728:Hormones / Q000097:blood*; D006801:Humans; D008297:Male; D008790:Metoprolol / Q000627:therapeutic use*; D008875:Middle Aged; D011674:Pulse
D000319:Adrenergic beta-Antagonists; D001786:Blood Glucose; D006728:Hormones; D008790:Metoprolol