Myocardial dysfunction, perfusion abnormalities, and the extent to which these abnormalities may be reversed by C-peptide administration was assessed in type 1 diabetic patients. Eight patients were studied before and during a 0.84-mg/kg dipyridamole administration using a randomized double-blind crossover protocol with infusion of C-peptide (6 pmol ⅐ kg -1 ⅐ min -1 ) or saline during 60 min on two different days. Myocardial function was measured as peak myocardial velocity during systole (Vs) and early diastole (Vd) by pulsed tissue Doppler imaging. Myocardial contrast echocardiography was used for assessment of myocardial blood volume (SI max ) and myocardial blood flow index (MBFI) calculated from the relation between trigger interval and signal intensity. Eight age-matched healthy volunteers served as control subjects. In the basal state, Vd (13.8 ؎ 0.6 vs. 15.6 ؎ 0.5 cm/s, P < 0.04) and SI max (6.6 ؎ 0.6 vs. 8.2 ؎ 0.6 a.u. P < 0.04) were reduced in patients compared with control subjects. Dipyridamole administration significantly increased indexes of myocardial function and blood flow to a similar extent in patients and control subjects. During C-peptide administration, Vs and Vd increased by 12% (P ‫؍‬ 0.03), SI max increased from 6.6 ؎ 0.6 to 8.1 ؎ 0.7 a.u. (P < 0.02), and MBFI increased from 3.3 ؎ 0.4 to 5.3 ؎ 0.9 (P < 0.05). The results demonstrate that type 1 diabetic patients have impaired myocardial function and perfusion in the basal state that can be improved by short-term replacement of C-peptide. Diabetes 51:3077-3082, 2002

Cardiac disease in diabetes mellitus and in the metabolic syndrome consists of both vascular and myocardial abnormalities. The latter are characterised predominantly by diastolic dysfunction, which has been difficult to evaluate in spite of its prevalence. While traditional Doppler echocardiographic parameters enable only semiquantitative assessment of diastolic function and cannot reliably distinguish perturbations in loading conditions from altered diastolic functions, new technologies enable detailed quantification of global and regional diastolic function. The most readily available technique for the quantification of subclinical diastolic dysfunction is tissue Doppler imaging, which has been integrated into routine contemporary clinical practice, whereas cine magnetic resonance imaging (CMR) remains a promising complementary research tool for investigating the molecular mechanisms of the disease. Diastolic function is reported to vary linearly with age in normal persons, decreasing by 0.16 cm/s each year. Diastolic function in diabetes and the metabolic syndrome is determined by cardiovascular risk factors that alter myocardial stiffness and myocardial energy availability/bioenergetics. The latter is corroborated by the improvement in diastolic function with improvement in metabolic control of diabetes by specific medical therapy or lifestyle modification. Accordingly, diastolic dysfunction reflects the structural and metabolic milieu in the myocardium, and may allow targeted therapeutic interventions to modulate cardiac metabolism to prevent heart failure in insulin resistance and diabetes.

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Quantification of diastolic myocardial function by pulsed Doppler myocardial mapping during dobutamine stress test was shown to be a feasible, accurate, reproducible, noninvasive technique that should be considered to be a sensitive alternative to the present echocardiographic and scintigraphic imaging techniques for stress tests.

Diastolic and systolic myocardial dysfunction in patients with type 2 diabetes may be identified by quantitative tissue Doppler imaging before the onset of clinical signs of heart failure and before the appearance of traditional echocardiographic indices of systolic myocardial dysfunction.

The physiological impact of age on myocardial function consists of a 1% annual reduction in E' and enables precise quantification of diastolic dysfunction thereby unmasking the importance of metabolic risk for DDF.

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In people with type 2 diabetes (T2DM), hyperglycemia has a negative impact on cardiac function and cardiovascular risk. Beneficial effects of improved postprandial glycemic control have been shown for cardiovascular risk only. To demonstrate these beneficial effects on myocardial function, we investigated well-controlled T2DM patients on three insulin regimens with different impact on postprandial glucose control. For 24 months, 61 T2DM participants in a randomized study had either conventional therapy (CT) with human premixed insulin b.d. (n=20), intensified therapy (ICT) with Lispro at meals and NPH at bedtime (n=24), or supplementary therapy (SIT) with human regular insulin at meals (n=17). Metabolism and cardiovascular function were assessed before and 2 hours after a standardized carbohydrate breakfast (48 g) using tissue Doppler to measure diastolic myocardial function (E'). Age, BMI, dose of insulin, cardiovascular disease, and medication were comparable between the groups. Hb1Ac was comparable with CT, ICT, and SIT (6.6+/-0.6, 6.2+/-0.6, and 6.4+/-0.7%) and so was fasting glucose. Post-meal glucose increment was 60+/-45 mg/dl with CT, but 15+/-52 and 8+/-58 mg/dl with ICT and SIT (p<0.006). E' was significantly lower (p<0.03) with CT (6.8+/-1.0 cm/s) vs. ICT (7.7+/-1.6) and SIT (7.8+/-1.2 cm/s), and correlated with post-meal glucose (r=-0.2644, p<0.046). Intima-media thickness and arterial stiffness parameters were higher in CT (p<0.04). In T2DM patients, the long-term insulin regimens CT, ICT, and SIT achieved overall good metabolic control with significant differences, however, in postprandial glucose increments. The regimens achieving better post-meal glucose control were associated with better myocardial/vascular function.