Too many highs and lows in glucose levels could be another reason that causes cardiovascular complications.
Dysglycemia is an abnormality that leads to glucose instability. Glycemic variability (GV) is one of the elements of dysglycemia. While severe glucose fluctuations, seen with hypoglycemic episodes, are known to be one of the factors for cardiovascular outcomes, the association between glycemic GV and the incidence of midterm major cardiac events (MACE) in individuals with diabetes stays uncertain.
The findings of a systemic literature review presented that GV is linked with development of microvascular complications such as retinopathy and nephropathy in patients with type 2 diabetes, but its role in terms of microvascular and macrovascular complications for patients with type 1 diabetes is still unclear.
Previous studies have been conducted to examine the relationship with hypoglycemic episodes during hospitalization and future morbidity or mortality in patients with type 2 diabetes and myocardial infarction. Upon data analysis, they concluded that hypoglycemia during the initial hospitalization was not an independent risk factor for prognosis in patients with diabetes and acute myocardial infarction.
A new study was conducted to examine the predictive ability of GV in regard to midterm MACE in patients with diabetes and acute coronary syndrome. This study included a total of 327 participants with diabetes and acute coronary syndrome who were admitted to the ICCU of Bordeaux University Hospital from January 2015 to November 2016.
Investigators evaluated each patient for glycemic variability at enrollment and monitored them for major cardiovascular events, such as new-onset myocardial infarction, acute heart failure, and cardiac death, during the follow-up period (May to August of 2017) .
Inclusion criteria of the study were defined as follows: a confirmed diagnosis of acute coronary syndrome and either type 1 or 2 diabetes (HbA1C ≥6.5% as admission), and an admission blood glucose of 16.7 mmol/L. Additionally, any patients who were admitted because of diabetic ketosis or nonketotic hyperosmolar coma or had an episode of acute transient elevation of blood glucose greater than 11 mmol/L, due to the stress of illness, during hospitalization were excluded from the study.
To measure the glycemic variability, researchers used the SD of serum glucose (mmol/L) collected by point of care glucometers during ICCU stay. To manage glycemia, patients received intravenous insulin therapy to reach the target blood glucose level between 7.77 and 10.0 mmol/L. Furthermore, patients with continuous insulin administration that was initiated when blood glucose greater than 10.0 mmol/L on admission or when premeal blood glucose was greater than 7.7 mmol/L, received continuous insulin therapy. In order to assess the differences between high and low levels of GV, the log-rank test was done. Also, Kaplan-Meier survival curves were used to represent the proportional risk of MACE for GV.
The results of data analysis reposted that there was a significant correlation between GV and admission glucose and HbA1c (P< 0.001). Also, it was noted that there was a significant association between GV and hypoglycemia episodes during the hospitalization for each patient (p<0.001).
Out of 327 patients in the study, a total of 89 patients (27.2%) experienced MACE with 24 deaths due to cardiac causes, 35 due to new-onset myocardial infarction (MI), and 30 hospital admissions due to acute heart failure. Based on the result of multivariable logistic regression analysis, it appeared that GV greater than 2.7mmol/L is one the independent predictive factors of midterm major cardiovascular events (odds ratio [OR], 2.21; 95% CI, 1.64-2.98; P <.001). Other independent predictive factors for MACE included an increased cardiac surgery score >34 and reduced LVEF <40%. However, it was noted that acute coronary events risk score >140 is not of the independent predictive factors for midterm MACE.
Researchers concluded that a GV cutoff value of greater than 2.70 mmol/L seems to be one the strongest independent predictive factors for midterm MACE in individuals with diabetes and acute coronary syndrome and a high GV should probably be avoided in these patients. GV also seems to be a better prognostic factor of midterm MACE than the GRACE score that is frequently used for risk stratification in ACS. This study suggests that clinicians should be alarmed for the potential of cardiovascular risk when there is a high GV exist. To further confirm these results, other prospective trials should be conducted.
- A high glycemic variability should be avoided in patients with diabetes and ACS.
- Glycemic variability might be a better predictor for midterm MACE than GRACE score.
- A GV limit of >2.7 mmol/L is the strongest independent predictive factor for midterm major adverse cardiac events in patients with diabetes and acute coronary syndrome,
References for “Using Glycemic Variability To Predict Major Cardiac Events In Patients with Type 2 Diabetes”:
Gerbaud, Edouard, et al. “Glycemic Variability Is a Powerful Independent Predictive Factor of Midterm Major Adverse Cardiac Events in Patients With Diabetes With Acute Coronary Syndrome.” Diabetes Care, American Diabetes Association, 5 Feb. 2019, care.diabetesjournals.org/content/early/2019/01/31/dc18-2047.
Mellbin LG, Malmberg K, Waldenström A, et al Prognostic implications of hypoglycaemic episodes during hospitalisation for myocardial infarction in patients with type 2 diabetes: a report from the DIGAMI 2 trial Heart 2009;95:721-727.
Ghazal Blair, Pharm.D. Candidate 2019, LECOM School of Pharmacy