Sensitivity to insulin during treatment with atenolol and metoprolol: a randomised, double blind study of effects on carbohydrate and lipoprotein metabolism in hypertensive patients.
OBJECTIVE
To compare the effects of metoprolol and atenolol on carbohydrate and lipid metabolism and on insulin response to an intravenous glucose load.


METHODS
Randomised, double blind, double dummy, controlled crossover trial.


METHODS
University Hospital, Uppsala, Sweden.


METHODS
60 Patients with primary hypertension (diastolic blood pressure when resting supine 95-119 mm Hg on at least two occasions during four to six weeks of treatment with placebo) randomised to receive either metoprolol (n = 30) or atenolol (n = 30) during the first treatment period.


METHODS
Placebo was given for a run in period of four to six weeks. Metoprolol 100 mg twice daily or atenolol 25 mg twice daily was then given for 16 weeks. The two drugs were then exchanged and treatment continued for a further 16 weeks.


METHODS
Evaluation of effects of treatment with metoprolol and atenolol on glucose, insulin, and lipid metabolism and glucose disposal mediated by insulin.


RESULTS
Reduction of blood pressure was similar and satisfactory during treatment with both drugs. Glucose uptake mediated by insulin was measured during a euglycaemic hyperinsulinaemic clamp to evaluate patients' sensitivity to insulin. Glucose uptake decreased from 5.6 to 4.5 mg/kg/min when patients were taking metoprolol and from 5.6 to 4.9 mg/kg/min when they were taking atenolol. Both drugs caused a small increase in fasting plasma insulin and blood glucose concentrations and glycated haemoglobin concentration. Despite decreased sensitivity to insulin the increase in insulin concentration in response to an intravenous glucose tolerance test was small, suggesting inhibition of release of insulin. Very low density lipoprotein and low density lipoprotein triglyceride concentrations were increased with both drugs and high density lipoprotein cholesterol concentration was decreased. Low density lipoprotein cholesterol concentration was not affected.


CONCLUSIONS
Long term use of metoprolol and atenolol causes metabolic abnormalities that may be related to the increased incidence of diabetes in patients with hypertension who are treated pharmacologically. These results may help to explain why the two drugs have failed consistently to reduce the incidence of coronary heart disease in several large scale studies.
Pollare
T
T
Department of Geriatrics, Uppsala University, Sweden.
Lithell
H
H
Selinus
I
I
Berne
C
C
D001262:Atenolol / Q000627:therapeutic use*; D001786:Blood Glucose / Q000378:metabolism*; D002784:Cholesterol / Q000097:blood; D002986:Clinical Trials as Topic; D004311:Double-Blind Method; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D006973:Hypertension / Q000097:blood* / Q000188:drug therapy; D007333:Insulin Resistance; D008074:Lipoproteins / Q000097:blood*; D008297:Male; D008790:Metoprolol / Q000627:therapeutic use*; D008875:Middle Aged; D011897:Random Allocation; D014280:Triglycerides / Q000097:blood
D001786:Blood Glucose; D008074:Lipoproteins; D014280:Triglycerides; D001262:Atenolol; D002784:Cholesterol; D008790:Metoprolol