The difficult task of glycaemic control in diabetics with acute coronary syndromes: finding the way to normoglycaemia avoiding both hyper- and hypoglycaemiaThe opinions expressed in this article are not necessarily those of the Editors of the European Heart Journal or of the European Society of Cardiology

Antonio Abbate, Giuseppe G.L. Biondi-Zoccai
2005 European Heart Journal  
This editorial refers to 'Association between hyperand hypoglycaemia and 2 year all-cause mortality risk in diabetic patients with acute coronary events' † by A.M. Svensson et al., on page 1255 Considering glycaemic control in diabetes, we often think that all metabolic syndromes are born equal and, as for cholesterolaemia, 'the less the better'. Perhaps not in diabetes. Diabetes mellitus is a metabolic syndrome characterized by absolute or relative insulin deficiency. Despite the simplicity of
more » ... the concept of insulin deficiency and hyperglycaemia, the mechanisms underlying the variable complications of diabetes are often unclear. Diabetics are a high cardiovascular risk population at increased risk of new or recurrent episodes of atherothrombosis, and these patients with acute coronary syndromes have the worse outcome when compared with nondiabetics, independently from the therapeutic approach. 1 Furthermore, even new onset stress hyperglycaemia in patients with acute myocardial infarction (AMI) predicts adverse outcome. 2,3 Nevertheless how much and how antidiabetic treatment affects survival in patient with AMI is still unclear. Svensson et al. 4 report the prognostic value of admission and in-hospital glycaemic values in patients admitted with AMI. The authors have studied more than 700 consecutive diabetic patients treated at a single institution and followed for .2 years. Mortality in this cohort was .30% at 2 years, and glycaemic control was predictive of outcome. 4 Interestingly, when compared with the patients with optimal in-hospital glycaemic control, those with suboptimal glycaemic control [lowest value 6.6 mmol/L (120 mg/dL)] and those with hypoglycaemia during the hospitalization [lowest value 3.0 mmol/L (55 mg/dL)] all had worse outcome at long-term follow-up. The authors conclude that 'in the setting of ACS among patients with diabetes, hyperglycaemia on arrival and hypoglycemia during hospitalization are both independently associated with the worse adjusted all-cause 2-year mortality risk'. 4 Although neither of these concepts is completely new, the association between in-hospital glycaemic control and long-term outcome is disturbing because a clear pathophysiologic explanation is lacking. Hyperglycaemia and adverse outcome: overwhelming evidence The negative prognostic value of hyperglycaemia at admission in AMI patients and acutely ill patients in general has been extensively reported and discussed. 2 While fasting hyperglycaemia in diabetes is the result of absolute or relative insulin deficiency, an acute increase in glycaemia related to increased activity of counterregulatory hormones is usually referred to as 'stress hyperglycaemia'. Stress is the physiologic/pathologic response to sudden changes in the homeostasis. In AMI, stress responses are aimed to optimize short-term cardiovascular performance and include both enhanced adrenergic and glucocorticoid response. The degree of hyperglycaemia may therefore reflect, to some extent, the underlying stress. This view of hyperglycaemia as a simple marker may, however, be inappropriate. Hyperglycaemia and myocardial metabolism One possible interpretation of the association between hyperglycaemia and adverse outcome is the consideration that, despite hyperglycaemia, the myocardium is actually in glucose starvation due to increased insulin-resistance, with a shift towards free fatty acid metabolism and impaired cardiac performance. 5,6 On this basis, the DIGAMI trial suggested that optimal glycaemic control with insulin in patients with AMI was beneficial by allowing intracellular glucose uptake by the ischaemic myocardium. 7 Failure to confirm these results by the very recent DIGAMI 2 trial, however, questions the validity of these concepts. 8 Nevertheless, the benefits of treatment of hyperglycaemia is unquestionable and optimal glycaemic control is
doi:10.1093/eurheartj/ehi302 pmid:15914500 fatcat:yvsuc4zmqbgw3fqayfkq6wlvgm