Cardiac events in 735 type 2 diabetic patients who underwent screening for unknown asymptomatic coronary heart disease: 5-year follow-up report from the Milan Study on Atherosclerosis and Diabetes (MiSAD).

OBJECTIVE: To report the cardiac events in type 2 diabetic outpatients screened for unknown asymptomatic coronary heart disease (CHD) and followed for 5 years. RESEARCH DESIGN AND METHODS: During 1993, 925 subjects aged 40-65 years underwent an exercise treadmill test (ETT). If it was abnormal, the subjects then underwent an exercise scintigraphy. Of the 925 subjects, 735 were followed for 5 years and cardiac events were recorded. RESULTS: At the entry of the study, 638 of the 735 followed subjects had normal ETT, 45 had abnormal ETT with normal scintigraphy, and 52 had abnormal ETT and abnormal scintigraphy. The 52 subjects with abnormal scintigraphy and ETT underwent a cardiological and diabetological follow-up; the subjects with just abnormal ETT had a diabetological follow-up only. During the follow-ups, 42 cardiac events occurred: 1 fatal myocardial infarction (MI), 20 nonfatal MIs, and 10 cases of angina in the 638 subjects with normal ETT; 1 fatal MI in the 45 subjects with normal scintigraphy; and 1 fatal MI and 9 cases of angina in the 52 subjects with abnormal scintigraphy. In these 52 subjects all cardiac events were significantly more frequent (chi(2) = 21.40, P < 0.0001) but the ratio of major (cardiac death and MI) to minor (angina) cardiac events was significantly lower (P = 0.002). Scintigraphy abnormality (hazard ratio 5.47; P < 0.001; 95% CI 2.43-12.29), diabetes duration (1.06; P = 0.021; 1.008-1.106), and diabetic retinopathy (2.371; P = 0.036; 1.059-5.307) were independent predictors of cardiac events on multivariate analysis. CONCLUSIONS: The low ratio of major to minor cardiac events in the positive scintigraphy group may suggest, although it does not prove, that the screening program followed by appropriate management was effective for the reduction of risk of major cardiac events.

Acidic and neutral sialidase in the erythrocyte membrane of type 2 diabetic patients.

The behavior of the 2 sialidase forms present in the erythrocyte membrane was investigated in 117 subjects with type 2 diabetes mellitus versus 95 healthy controls. A significant increase of the acidic form of sialidase, which is anchored to the membrane by a glycosylphosphatidylinositol bridge, was observed in erythrocyte resealed membranes. On the contrary, the neutral form of the enzyme, the only one capable of removing lipid- and protein-bound sialic acid from endogenous and exogenous sialoderivatives, was significantly reduced with a consequent increase of erythrocyte membrane total sialic acid content. Disease duration, therapy, glycemia, parameters of metabolic control, and presence of complications, except nephropathies, had no influence on the tested enzyme activities. Diabetic subjects showed a different erythrocyte age distribution, with an almost double proportion of young red cells and only one quarter of senescent ones compared with controls. In young erythrocytes, diabetic and control subjects had the same distribution of the 2 enzymes, while in senescent cells the acidic enzyme was increased 3.5-fold and the neutral form was reduced by half in the diabetic subjects. The increase of both acidic sialidase and total membrane-bound sialic acid, together with an overpresence of young red cells in diabetics, suggests that in this pathological condition there might be an altered aging process with a diminished expression of the neutral form of the enzyme and an increase of bound sialic acid. It has been suggested that the expression of the neutral enzyme requires some activation mechanism that is impaired in diabetes.