Left ventricular diastolic (dys)function in type 2 diabetes: time for a critical reappraisal

Calcium signaling in diabetic cardiomyocytes

Diabetes mellitus is one of the most common medical conditions. It is associated to medical complications in numerous organs and tissues, of which the heart is one of the most important and most prevalent organs affected by this disease. In fact, cardiovascular complications are the most common cause of death among diabetic patients. At the end of the 19th century, the weakness of the heart in diabetes was noted as part of the general muscular weakness that exists in that disease. However, it was only in the eighties that diabetic cardiomyopathy was recognized, which comprises structural and functional abnormalities in the myocardium in diabetic patients even in the absence of coronary artery disease or hypertension. This disorder has been associated with both type 1 and type 2 diabetes, and is characterized by early-onset diastolic dysfunction and late-onset systolic dysfunction, in which alteration in Ca(2+) signaling is of major importance, since it controls not only contraction, but also excitability (and therefore is involved in rhythmic disorder), enzymatic activity, and gene transcription. Here we attempt to give a brief overview of Ca(2+) fluxes alteration reported on diabetes, and provide some new data on differential modulation of Ca(2+) handling alteration in males and females type 2 diabetic mice to promote further research. Due to space limitations, we apologize for those authors whose important work is not cited.

Diabetic cardiomyopathy: myth or reality?

Diabetes mellitus has reached an epidemic level worldwide. Cardiovascular diseases are the primary cause of death in diabetic patients, not only because of coronary artery disease and associated hypertension but also because of a direct adverse effect of diabetes on the heart, independent of other potential aetiological factors. However, the existence of this 'diabetic cardiomyopathy' remains controversial. We aimed to review current evidence for the existence of diabetic cardiomyopathy, focusing particularly on the clinical setting.

B-type natriuretic peptide, a marker of asymptomatic left ventricular dysfunction in type 2 diabetic patients

AIM

To evaluate BNP in assessing LV functions in asymptomatic type 2 diabetic patients.

METHODS

BNP was measured in 91 consecutive patients with type 2 diabetes mellitus. According to Doppler echocardiography, patients were first separated into three categories: normal LV function, or isolated diastolic or systolic LV dysfunction. As some patients with diastolic dysfunction were treated for hypertension, the population was divided into four groups: groups 1, 2 and 3 all had no antihypertensive treatment, and had normal LV function, and isolated diastolic and systolic LV dysfunction, respectively; and group 4 were being treated with antihypertensive drugs and had diastolic LV dysfunction.

RESULTS

In group 1, BNP levels (13+/-2 ng/L) were lower than in group 2 (87+/-20 ng/L, P<0.0001) or group 3 (213+/-32 ng/L, P<0.0001), but were similar to those of group 4 (32+/-6 ng/L, P=0.14). ROC analysis revealed a rule-out value of 23 ng/L for group 1 versus group 2, and of 239 ng/L for group 2 versus group 3. In groups 1, 2 and 3 taken together, BNP levels were correlated with urinary albumin excretion rate (r=0.80, P<0.0001) and pulse pressure (r=0.65, P<0.0001). In group 4, patients receiving ACE inhibitors had lower BNP levels than those receiving ss-blockers.

CONCLUSION

BNP can be used to pre-screen asymptomatic type 2 diabetic patients with LV dysfunction, and may reveal vascular remodelling in type 2 diabetes mellitus.