The burden of rupture-prone atherosclerotic plaque increases with the duration of diabetes mellitus, a study using intravascular ultrasound (IVUS) has found.

The finding may explain, in part, why the risk for coronary heart disease rises with increasing duration of diabetes mellitus, say the researchers writing in the journal Circulation: Cardiovascular Interventions.

For the study, Steven Marso (University of Missouri, Kansas City, USA) and co-workers used IVUS and virtual histology to investigate the relationship between thin-cap fibroatheroma and diabetes duration.

Thin-cap fibroatheromatous plaques are characterized by a necrotic core, intraplaque hemorrhage, calcification, and a thin layer of connective tissue, and are particularly susceptible to rupture, explain the researchers.

The study participants were 54 diabetic individuals undergoing diagnostic coronary angiography, of whom 26 had been diagnosed with diabetes for less than 10 years and 28 had suffered from the disease for 10 year or longer.

Those with a longer duration of diabetes were older, less likely to have a history of tobacco use, had higher total cholesterol levels, and were more likely to be treated with insulin than those with a shorter duration of diabetes.

Furthermore, the total plaque burden was significantly greater in patients with a longer duration of diabetes, at 60.4% in those with diabetes for 10 or more years versus 50.2% for those with diabetes for less than 10 years.

The distribution of plaque phenotypes also differed by diabetes duration, with thin-cap fibroatheroma accounting for just 10.8% of plaques in those with diabetes for less than 10 years versus 54.4% of plaques in those with diabetes for 10 or more years. This difference was highly statistically significant and remained so after adjustment for multiple comparisons, clinical characteristics, and diabetes treatment.

Noting that thin-cap fibroatheroma is associated with an increased risk for coronary thrombosis and cardiovascular death, Marso et al conclude that not only the presence but also the duration of diabetes “contribute to high-risk atherosclerotic phenotypes.”

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2009

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Diabetic retinopathy is associated with visceral fat accumulation and insulin resistance in patients with Type 2 diabetes, study results show.

Futoshi Anan (Oita Red Cross Hospital, Japan) and co-workers explain that “increased visceral fat accumulation is a risk factor for cardiovascular disease and is associated with insulin resistance in healthy subjects and patients with Type 2 diabetes mellitus.”

Furthermore, the researchers add that “the presence of diabetic retinopathy is reported to be associated with insulin resistance in Type 2 diabetes mellitus patients.”

Based on these observations, Anan and team hypothesized that increased severity of diabetic retinopathy is associated with visceral fat accumulation and insulin resistance in patients with Type 2 diabetes mellitus.

The scientists studied 31 patients with Type 2 diabetes and 71 patients with both Type 2 diabetes and diabetic retinopathy, all of whom were Japanese.

Analysis of visceral fat levels and insulin sensitivity revealed that the risk for diabetic retinopathy was significantly, positively, and independently predicted by visceral fat accumulation and degree of insulin resistance. These associations remained after controlling for potential confounders, including age, gender, body mass index, waist circumference, duration of diabetes, hypertension, dyslipidemia, blood pressure, and lipid concentrations.

The authors concede in the journal Metabolism: Clinical and Experimental that their study is limited because none of the patients underwent coronary angiography and so the potential influence of cardiovascular disease on the relationships between visceral fat accumulation and retinopathy could not be accounted for.

However, despite these and other limitations, they conclude that the findings provide early evidence for links between diabetic retinopathy and elevated levels of visceral fatty acid accumulation and insulin resistance, which deserves further study.

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2009

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Patients with diabetes mellitus exhibit impaired systolic and diastolic function even in the absence of coronary artery disease (CAD), Danish researchers have shown.

Noting that myocardial dysfunction is a marker of adverse prognosis, they recommend that diabetes patients should be regarded as a high-risk group, even when standard coronary angiography and echocardiography results are normal.

Charlotte Andersson (University of Copenhagen) and co-workers assessed cardiac function in 31 patients with diabetes and 31 healthy controls matched for age, gender, and presence of hypertension. All participants had a left ventricular ejection fraction (LVEF) above 35% and none had significant CAD or other heart disease.

“Patients with diabetes mellitus have high risk of heart failure,” they explain. “Whether some of the risk is directly linked to metabolic derangements in the myocardium or whether the risk is primarily caused by CAD and hypertension is incompletely understood.”

The participants underwent echocardiographic tissue Doppler imaging to assess myocardial function.

Writing in the journal Cardiovascular Diabetology, Andersson et al reveal that mean LVEF, mean left atrial end-systolic volume, mean LV dimensions, and prevalence of diastolic dysfunction were comparable between participants with and without diabetes.

However, diabetes patients had significantly reduced measures of global longitudinal strain (15.9% vs 17.7%), peak longitudinal systolic velocity (5.7 vs 6.4 cm/s) and early diastolic velocity (6.1 vs 7.7 cm/s) compared with controls.

Furthermore, in multivariable regression analyses, diabetes remained associated with impairments in both peak systolic and early diastolic tissue velocities, with mean values in diabetes patients being 89% and 79%, respectively, of those in controls. The presence of hypertension did not modify these findings.

The researchers remark that the Doppler-detected abnormalities observed in diabetes patients were not identifiable from any of the conventional echocardiographic parameters; the findings are therefore “directly applicable to everyday clinical practice.”

“In a clinical context, the subclinical impairments of left ventricular function in patients with diabetes mellitus recognized to carry an adverse prognosis,” they write.

“The results from the present study further emphasize that patients with diabetes mellitus should continuously be regarded as a high-risk group, even when cardiac angiography and conventional echocardiography investigations appear normal.”

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

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