Beta blockers and hyperglycemia

Betal 2 Receptors have an important role in hepatic glucose production in humans and may contribute to hypoglycemia associated with unselective beta-blockade (1) e.g. use of propranolol rather than the use of beta-1 selective blockers e.g. atenolol, metoprolol.

• beta -2-adrenergic antagonism has a role in the inhibition of hepatic gluconeogenesis
  
  
• therefore was believed that selective beta-1 blockers would not lead to hypoglycaemia - however "...in patients with abnormal energy requirements or metabolism, administration of beta 1-selective-adrenergic antagonists may be associated with hypoglycaemia..."(2)

Beta blockers in diabetes and insulin resistance:

• studies, such as the Losartan Intervention for Endpoint Reduction in Hypertension Study (LIFE) (3) with atenolol, the Carvedilol or Metoprolol European Trial (COMET) (4) with metoprolol have shown a 22% to 28% increase of new-onset diabetes with traditional beta beta-blockers that can increase insulin resistance (and hence hyperglycaemia) (5)
• side effects of beta -blockers in the patient with diabetes include increased insulin resistance with worsening glycemic control
• increased frequency of hypoglycemia and its lack of recognition can also be a problem in the insulin-deficient patient but is a minimal problem with the patient with type 2 diabetes (5)
• there is evidence that some beta-blockers may have 'insulin-sensitising properties' (5)
  • carvedilol, a nonselective beta-blocker had vasodilating and insulin-sensitizing properties, and is the ideal beta-blocker for the patient with diabetes (5)
  • carvedilol is a third generation beta-blocker in comparison with atenolol which is a second generation beta blocker

Reference:

• 1) William-Olsson T, Fellenius E, Bjorntorp P, Smith U. Differences in metabolic responses to beta-adrenergic stimulation after propranolol or metoprolol administration. Acta Med Scand 1979; 205: 201-6
• 2)Brown DR, Brown MJ. Hypoglycemia associated with preoperative metoprolol administration. Anesth Analg. 2004 Nov;99(5):1427-8;
• 3) Dahlof B, Devereux RB, Kjeldsen SE, Julius S, Beevers G, de Faire U, Fyhrquist F, Ibsen H, Kristiansson K, Lederballe-Pedersen O, et al; LIFE Study Group. Cardiovascular morbidity and mortality in the Losartan Intervention For Endpoint reduction in hypertension study (LIFE): a randomised trial against atenolol. Lancet 2002;359:995-1003
• 4) Carvedilol Or Metoprolol European Trial (COMET). Hospitalizations and predefined secondary endpoints. Presented at the Heart Failure Society of America 77th Annual Scientific Meeting Breakfast Satellite Symposium; September 22, 2003; Las Vegas, Nevada
• 5) Bell DS. Advantages of a third-generation beta-blocker in patients with diabetes mellitus. Am J Cardiol. 2004 May 6;93(9A):49B-52B