Relationship of the total atrial conduction time to subclinical atherosclerosis, inflammation and echocardiographic parameters in patients with type 2 diabetes mellitus

OBJECTIVES

The aim of our study was to evaluate the total atrial conduction time and its relationship to subclinical atherosclerosis, inflammation and echocardiographic parameters in patients with type 2 diabetes mellitus.

METHODS

A total of 132 patients with type 2 diabetes mellitus (mean age 54.5 ± 9.6 years; 57.6% male) and 80 age- and gender-matched controls were evaluated. The total atrial conduction time was measured by tissue-Doppler imaging and the carotid intima-media thickness was measured by B-mode ultrasonography.

RESULTS

The total atrial conduction time was significantly longer in the patients with type 2 diabetes mellitus than in the control group (131.7 ± 23.6 vs. 113.1 ± 21.3, p<0.001). The patients with type 2 diabetes mellitus had significantly increased carotid intima-media thicknesses, neutrophil to lymphocyte ratios and high-sensitivity C-reactive protein levels than those of the controls. The total atrial conduction time was positively correlated with the high-sensitivity C-reactive protein level, neutrophil to lymphocyte ratio, carotid intima-media thickness and left atrial volume index and negatively correlated with the early diastolic velocity (Em), Em/late diastolic velocity (Am) ratio and global peak left atrial longitudinal strain. A multiple logistic regression analysis demonstrated that the neutrophil to lymphocyte ratio, carotid intima-media thickness and global peak left atrial longitudinal strain were independent predictors of the total atrial conduction time.

CONCLUSIONS

We suggest that subclinical atherosclerosis and inflammation may represent a mechanism related to prolonged total atrial conduction time and that prolonged total atrial conduction time and impaired left atrial myocardial deformation may be represent early subclinical cardiac involvement in patients with type 2 diabetes mellitus.

Intensive glucose control and hypoglycaemia: a new cardiovascular risk factor?

Intensive glucose control is widely practiced in patients with diabetes mellitus and patients acutely admitted to hospitals with concomitant stress-induced hyperglycaemia. Such a strategy increases the risk of hypoglycaemia by several-fold. Hypoglycaemia leads to a surge in catecholamine levels with a profound haemodynamic response. In patients with a decreased cardiac reserve, such significant changes can culminate in serious or even fatal cardiovascular outcomes. This review is aimed at discussing in depth the evidence to date that links hypoglycaemia with cardiovascular mortality, reviewing the likely mechanisms underlying this association, as well as summarising these from a cardiologist's perspective.

A multiple-ascending-dose study to evaluate safety, pharmacokinetics, and pharmacodynamics of a novel GPR40 agonist, TAK-875, in subjects with type 2 diabetes

G-protein-coupled receptor 40 (GPR40), highly expressed in pancreatic β-cells, mediates free fatty acid (FFA)-induced insulin secretion. This phase I, double-blind, randomized study investigated the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of a novel, glucose-lowering GPR40 agonist, TAK-875 (q.d., orally × 14 days), in type 2 diabetics (placebo, n = 14; at 25, 50, 100, 200, or 400 mg, n = 45). Approximately dose-proportional increases in AUC(0-24) and C(max) occurred. TAK-875 showed good tolerability with no dose-limiting side effects. Two subjects (on TAK-875) had mild hypoglycemia, probably related to prolonged fasting after oral glucose tolerance tests (OGTTs). TAK-875 showed reductions from baseline in fasting (2 to -93 mg/dl) and post-OGTT glucose (26 to -172 mg/dl), with an apparent dose-dependent increase in post-OGTT C-peptide over 14 days. Consistent with preclinical data, TAK-875 apparently acts as a glucose-dependent insulinotropic agent with low hypoglycemic risk. Its PK is suitable for once-daily oral administration.

Repetitive hypoglycaemia increases serum adrenaline and induces monocyte adhesion to the endothelium in rat thoracic aorta

AIMS/HYPOTHESIS

Severe hypoglycaemia associated with diabetes management is a potential risk for cardiovascular diseases. However, the effect and mechanism of hypoglycaemia on the progression of atherosclerosis remains largely unknown. As a first step towards elucidating the above, we investigated the effect of hypoglycaemia on monocyte-endothelial interaction.

METHODS

Insulin was injected intraperitoneally once every 3 days for 5 weeks in Goto-Kakizaki rats, a non-obese rat model of type 2 diabetes. We counted the number of monocytes adherent to the endothelium of thoracic aorta as an index of early atherosclerogenesis. Cultured HUVEC were used to investigate the mechanism of action.

RESULTS

Insulin treatment increased the number of monocytes adherent to the vascular endothelium. This increase was abrogated by injection of glucose with insulin. Amosulalol, an α-1 and β-adrenoreceptor antagonist, suppressed monocyte adhesion to endothelium and levels of adhesion molecules (intercellular adhesion molecule-1 and vascular cell adhesion molecule-1) in the endothelial surface, which had been enhanced by insulin-induced hypoglycaemia. In HUVEC, adrenaline (epinephrine) significantly increased nuclear translocation of nuclear factor-κB (NF-κB) p65 and levels of adhesion molecules, effects that were abrogated following addition of SQ22536, a specific adenyl cyclase inhibitor.

CONCLUSIONS/INTERPRETATION

Our data indicate that repetitive hypoglycaemia induced by insulin enhanced monocyte adhesion to endothelial cells in Goto-Kakizaki rat aorta through enhanced adrenaline activity and that the latter stimulated intracellular cAMP, leading to nuclear translocation of NF-κB with subsequent production of adhesion molecules in endothelial cells.

Central nervous system: a conductor orchestrating metabolic regulations harmed by both hyperglycaemia and hypoglycaemia

Recent evidence suggests that the brain has a key role in the control of energy metabolism, body fat content and glucose metabolism. Neuronal systems, which regulate energy intake, energy expenditure, and endogenous glucose production, sense and respond to input from hormonal and nutrient-related signals that convey information regarding both body energy stores and current energy availability. In response to this input, adaptive changes occur that promote energy homeostasis and the maintenance of blood glucose levels in the normal range. Defects in this control system are implicated in the link between obesity and type 2 diabetes mellitus. The central nervous system may be considered the conductor of an orchestra involving many peripheral organs involved in these homeostatic processes. However, the brain is mainly a glucose-dependent organ, which can be damaged by both hypoglycaemia and hyperglycaemia. Hypoglycaemia unawareness is a major problem in clinical practice and is associated with an increased risk of coma. Stroke is another acute complication associated with diabetes mellitus, especially in elderly people, and the control of glucose level in this emergency situation remains challenging. The prognosis of stroke is worse in diabetic patients and both its prevention and management in at-risk patients should be improved. Finally, chronic diabetic encephalopathies, which may lead to cognitive dysfunction and even dementia, are also recognized. They may result from recurrent hypoglycaemia and/or from chronic hyperglycaemia leading to cerebral vascular damage. Functional imaging is of interest for exploring diabetes-associated cerebral abnormalities. Thus, the intimate relationship between the brain and diabetes is increasingly acknowledged in both research and clinical practice.

Endocrine and metabolic emergencies: hypoglycaemia

Hypoglycaemia is rare in healthy individuals owing to the numerous elegant hormonal and neuronal mechanisms that maintain glucose homeostasis. Glucose is an obligate metabolic fuel for cerebral tissue and therefore hypoglycaemia, if uncorrected, can have disastrous consequences including death. Clinical hypoglycaemia is defined as a plasma (or serum) glucose concentration low enough to cause symptoms and/or signs, including impairment of brain function. However, no single plasma (or serum) glucose concentration categorically defines hypoglycaemia. Hypoglycaemia is probably the most common endocrine and metabolic emergency in clinical practice. The overwhelming majority of occurrences of hypoglycaemia occur in patients with diabetes, either as a result of treatment-induced hypoglycaemia and/or abnormalities that affect the normal counterregulatory response to hypoglycaemia. The differential for nondiabetes-associated hypoglycaemia is broad and includes insulinoma, drugs, hormone deficiencies, and critical illness. The acute management of hypoglycaemia is discussed along with a review of the pathophysiology and aetiology of this commonly encountered clinical problem.