Per Anton Sirnes, Cardiology Consultant, Moss, Norway and Guy De Backer, Emeritus Professor, Ghent University, Belgium
Diabetes mellitus (DM) is a major health problem with a lifetime risk of 30–40% in European populations. It is estimated that there were 360 million people with DM in 2011, which by 2030 will have increased to 550 million, half of whom will be unaware of their diagnosis. In addition, about the same number have pre-diabetic states like impaired fasting glucose, impaired glucose tolerance, gestational diabetes and euglycaemic insulin resistance. The definitions and implications of these syndromes are thoroughly discussed in these guidelines, a 106-page document with 546 references freely downloadable from the ESC website.
The guidelines are written with a focus on the management of the combination of CVD (or risk of CVD) and DM. The document describes diagnostic criteria, and in principle concurs with the WHO and ADA criteria with emphasis on fasting plasma glucose >7.0 mmol/L (126 mg/dL) or 2-hour post glucose loading values >11.2 mmol/L (200 mg/dL). HbA1c (>6.5%) can be used, but there remains concern about its sensitivity. It is thus recommended that the diagnosis of diabetes is based on HbA1c and FPG combined, or on an OGTT if still in doubt. Definition and aetiology of the four main categories of DM (type 1 DM, type 2 DM, other specific DM, gestational DM) are discussed. For patients with CVD an OGTT is often needed if FPG or HbA1c are inconclusive.
Risk stratification should always be considered as part of a multifactorial evaluation. According to the 2012 ESC prevention guidelines, all patients with DM and at least one additional CV risk factor or evidence of target organ damage are at very high CV risk. All other subjects with DM are at high risk. Screening of hyperglycaemia for CV risk purposes should be targeted to high risk individuals. The mechanism of how hyperglycaemia and insulin resistance promotes atherosclerosis, thrombosis and endothelial dysfunction is discussed.
A large chapter describes in detail the importance of lifestyle modification for patients with DM. The importance of smoking cessation and frequent physical exercise is highlighted. Total fat intake should be <35%, saturated fat <10%, and monounsaturated fatty acids >10% of the total energy. A strict low carbohydrate diet is not recommended.
Glucose control should be individualised, taking into account duration of DM, co-morbidities and age. A target of HbA1c near normal (<7%) is recommended to decrease micro- and macrovascular complications. For type 1 DM a regimen of basal bolus insulin with frequent glucose monitoring is recommended, while for type 2 metformin should be first-line therapy. The use of other hypoglycaemic agents is discussed in detail.
Good blood pressure control is of great importance in patients with DM, with target levels of <140/85 mm Hg. This is in accordance with the 2013 ESC/ESH hypertension guidelines and somewhat more conservative than in previous recommendations. Any drug that lowers blood pressure adequately is in principle useful but an ACE-inhibitor (or if not tolerated an ARB) is recommended in the treatment of hypertension in DM, particularly in the presence of proteinuria or microalbuminuria. Drugs with negative metabolic effects, especially the combination of a diuretic and a beta-blocker, should be avoided as first-line treatment in hypertensive patients with metabolic syndrome.
Dyslipidaemia is one of the major risk factors for patients with DM and should be treated aggressively with an LDL-C target of <1.8 mmol/L (<70 mg/dL) or at least a ≥50% LDL-C reduction in patients at very high risk. Smoking cessation, increased physical activity, weight reduction and decreased consumption of fast-absorbed carbohydrates remains the only proven therapy with positive clinical outcome for raising HDL-C levels.
Primary prevention with aspirin is not recommended in patients with DM and low CV risk, but may be considered in those with very high risk on an individual basis. As secondary prevention patients with DM should be treated with antiplatelet agents according to ESC guidelines on stable CVD and ACS.
The management of patients with DM and established CVD is discussed thoroughly and concurs with the recent ESC guidelines on stable and unstable CAD. Patients with heart failure and DM should be treated as described in the recent ESC heart failure guidelines. Metformin is still the first choice in DM patients and HF, while thiazolidinedione drugs are contraindicated. DM is a major risk factor for stroke in patients with atrial fibrillation and should result in anticoagulation. Screening for AF should be considered. Similarly, peripheral artery disease is common in patients with DM and an annual screening is recommended.
A patient-centred care-model including cognitive behavioural strategies is recommended to facilitate shared control and decision-making within the context of patient priorities and goals and to help patients achieve lifestyle changes.