Prevalence of pre-existing dysglycaemia among inpatients with acute coronary syndrome and associations with outcomes

Prediabetes is Associated with Worse Long-Term Outcomes in Young Patients with Acute Coronary Syndrome

Purpose

The incidence of prediabetes mellitus (pre-DM) is increasing among young individuals. Whether pre-DM can predict adverse cardiovascular events in acute coronary syndrome (ACS) patients remains controversial. This study aimed to investigate the impact of pre-DM on the long-term clinical outcomes of patients aged≤ 45 years with new-onset ACS.

Patients and methods

A total of 1113 patients with new-onset ACS (aged≤ 45 years) who underwent percutaneous coronary intervention (PCI) were enrolled in this study. Patients were divided into three groups according to their glycemic status or history: normal glucose metabolism (NGM), prediabetes (pre-DM), and diabetes mellitus (DM). The primary endpoint was defined as a composite of major adverse cardiovascular events (MACE) including all-cause death, myocardial infarction (MI), stroke, or unplanned repeat revascularization. Multivariate Cox regression analysis was performed to explore the association between abnormal glycemic status and MACE.

Results

The prevalence of NGM, pre-DM, and DM were 45.9% (n=511), 27.0% (n=301), and 27.0% (n=301), respectively. During a median follow-up of 65 months, MACE occurred in 23.5% (n=120) of NGM, 29.2% (n=88) of pre-DM, and 34.6% (n=104) of DM (P=0.003). After multivariate adjustment, both pre-DM and DM significantly increased the risk of MACE compared with the NGM group (pre-DM: HR1.38, CI95% 1.05-1.83, P=0.023; DM: HR1.65, CI95% 1.27-2.16, P<0.001). Moreover, pre-DM had a similar impact on MACE as DM in young patients with ACS (P=0.162).

Conclusion

Pre-DM was common among patients aged≤ 45 years with new-onset ACS. Pre-DM was associated with an increased risk of future MACE compared to NGM.

Should Prediabetes be Treated Pharmacologically?

OBJECTIVE

In this commentary I will evaluate whether prediabetes should be treated pharmacologically. To consider this question, certain information concerning prediabetes is relevant.

BACKGROUND INFORMATION

(1) Prediabetes is not independently associated with cardiovascular disease; the other factors in the metabolic syndrome increase that risk; (2) various tests and criteria for diagnosing prediabetes are recommended, yielding prevalences varying from 6% to 38% depending on which are used; (3) one-third of patients with prediabetes revert to normal over time; (4) up to two-thirds of patients with prediabetes do not develop diabetes; (5) people with prediabetes have insulin resistance and impaired insulin secretion; (6) although pharmacological treatment of the dysglycemia temporarily lowers it, when the drugs are discontinued, incident diabetes develops similarly as that in those who received placebos; (7) when the drugs are discontinued, there are no changes in insulin resistance or impaired insulin secretion; (8) incident diabetes was similar at 10 years in people remaining on metformin in the Diabetes Prevention Program Outcome Study compared with those who did not receive the drug; (9) no current drugs will directly increase insulin secretion (except sulfonylureas and glinides which have not been used to treat prediabetes because of hypoglycemia concerns); (10) sufficient weight loss to lower insulin resistance by nutritional means is challenging and especially difficult to maintain.

CONCLUSIONS

Pharmacological treatment of the dysglycemia of prediabetes is not warranted. On the other hand, the ability of high doses of glucagon-like peptide (GLP)-1 receptor agonists and the combination of a GLP-1 receptor agonist and the glucose-dependent insulinotropic polypeptide (GIP) to lower weight by 15% and 20%, respectively, deserves consideration for the treatment of prediabetes. This amount of weight loss should decrease insulin resistance, allowing endogenous insulin secretion to be more effective and lower the risk for developing diabetes.

Historical review of the diagnosis of prediabetes/intermediate hyperglycemia: Case for the international criteria

In 1997, the ADA recommended an IFG criterion for diagnosing prediabetes/intermediate hyperglycemia of FPG concentrations of 6.1-6.9 mmol/L (110-125 mg/dL). In 2003, they lowered it to 5.6-6.9 mmol/L (100-125 mg/dL) to equalize developing diabetes between IGT and IFG. International organizations accepted the first IFG criterion but not the second. The ADA subsequently recommended HbA1c levels for diagnosing prediabetes/intermediate hyperglycemia of 39-47 mmol/mol (5.7-6.4%) based on a model that utilized the composite risk of developing diabetes and CVD. However, the evidence that the intermediate hyperglycemia that defines prediabetes is independently associated with CVD is weak. Rather, the other risk factors for CVD in the metabolic syndrome are responsible. The WHO opined that prediabetes/intermediate hyperglycemia could not be diagnosed by HbA1c levels but the Canadians and Europeans recommended its diagnosis by values of 42-47 mmol/mol (6.0-6.4%). With the ADA criteria, approximately one-half of people are normal on re-testing, one-third spontaneously revert to normal over time and two-thirds never develop diabetes in their lifetimes. The international criteria for prediabetes/intermediate hyperglycemia increase the risk of developing diabetes and might motivate these individuals to more seriously undertake lifestyle interventions as a preventive measure.

Metformin Should Not Be Used to Treat Prediabetes

Based on the results of the Diabetes Prevention Program Outcomes Study (DPPOS), in which metformin significantly decreased the development of diabetes in individuals with baseline fasting plasma glucose (FPG) concentrations of 110-125 vs. 100-109 mg/dL (6.1-6.9 vs. 5.6-6.0 mmol/L) and A1C levels 6.0-6.4% (42-46 mmol/mol) vs. <6.0% and in women with a history of gestational diabetes mellitus, it has been suggested that metformin should be used to treat people with prediabetes. Since the association between prediabetes and cardiovascular disease is due to the associated nonglycemic risk factors in people with prediabetes, not to the slightly increased glycemia, the only reason to treat with metformin is to delay or prevent the development of diabetes. There are three reasons not to do so. First, approximately two-thirds of people with prediabetes do not develop diabetes, even after many years. Second, approximately one-third of people with prediabetes return to normal glucose regulation. Third, people who meet the glycemic criteria for prediabetes are not at risk for the microvascular complications of diabetes and thus metformin treatment will not affect this important outcome. Why put people who are not at risk for the microvascular complications of diabetes on a drug (possibly for the rest of their lives) that has no immediate advantage except to lower subdiabetes glycemia to even lower levels? Rather, individuals at the highest risk for developing diabetes-i.e., those with FPG concentrations of 110-125 mg/dL (6.1-6.9 mmol/L) or A1C levels of 6.0-6.4% (42-46 mmol/mol) or women with a history of gestational diabetes mellitus-should be followed closely and metformin immediately introduced only when they are diagnosed with diabetes.

The Prevalence of Elevated Lipoprotein(a) in Patients Presenting With Coronary Artery Disease

BACKGROUND

Elevated lipoprotein(a) (Lp(a)) is an inherited lipid disorder and an independent risk factor for cardiovascular (CV) disease. Although its prevalence in the general population has been well-documented, the prevalence of elevated Lp(a) in patients with clinical coronary artery disease (CAD) is less clear. In this study, we hypothesised that there is an over-representation of elevated Lp(a) in patients with early-onset CAD compared to the general population.

METHODS

Between 6 February and 8 June 2018, we screened consecutive patients aged ≤70 years who presented to the Austin Hospital with any of the following criteria: (1) acute coronary syndrome (ACS); (2) percutaneous coronary intervention (PCI); or (3) coronary artery bypass grafting (CABG). Whilst examining a range of different Lp(a) levels, a dichotomous elevated Lp(a) was defined as concentrations ≥0.5 g/L. Other CV risk factors were documented including hypertension, type 2 diabetes mellitus, and familial hypercholesterolaemia (FH) using the Dutch Lipid Clinic Network Criteria (DLCNC), also incorporating family history and clinical examination.

RESULTS

One hundred and fifty-eight (158) patients were screened; 63 (39.9%) were under 60 years of age. Overall, elevated Lp(a) ≥0.5 g/L was identified in 57 patients (36.1%). Of these, nine patients (15.8%) also had probable or definite FH. General population data was obtained from the Copenhagen General Population Study which studied 6,000 men and women and showed that the estimated prevalence of Lp(a) ≥0.5 g/L in the general population was 20%.

CONCLUSIONS

Elevated Lp(a) is more prevalent in patients with relatively early-onset CAD compared to the general population and may contribute to previously unappreciated residual cardiovascular risk. Patients who present with early-onset CAD, should be routinely screened for elevated Lp(a).