Micro- and macrovascular complications and hyperhomocysteinaemia in type 1 diabetic patients

To determine the range of plasma homocysteine values in a cohort of type 1 diabetic subjects and to analyse the relationship between homocysteine levels and chronic degenerative complications.

71 type 1 diabetic inpatients admitted for poor glycaemic control and/or treatment of complications, especially macroangiopathic, were included in this study. Chronic diabetic complications, smoking prevalence, as well as current use of drugs were recorded, alongside fasting plasma homocysteine.

Age and diabetes duration were 51 (34-63) and 23 (13-32) years respectively (median [percentile 25-75]). HbA(1)c was 9.3% (8.2-10.5). Homocysteine was 9.2 (7.1-13.6) micromol/l, and 17% of patients had elevated homocysteinaemia on the basis of a laboratory cutoff value of 15 micromol/l. Folic acid and vitamin B(12) levels were within the normal range. Univariate statistical analysis showed a significant positive association between homocysteine and age (P<0.001), diabetes duration (P<0.001), systolic blood pressure (P<0.001), plasma creatinine (P<0.001), cholesterol/HDL-C (P=0.021) as well as with retinopathy (P=0.016) and all complications (P<0.001), and a negative correlation with folic acid (P=0.004) and creatinine clearance (P<0.001). Using a multiple regression analysis taking into account major variables, we confirmed an independent association of homocysteine with age (P=0.003), creatinine (P<0.001) and folic acid (P=0.014), but not with vascular complications.

Increased homocysteine is present in 17% of a limited group of poorly controlled type 1 diabetic patients, and is associated with age, creatinine and folic acid levels. In this type 1 population, there was no independent correlation of homocysteine with vascular complications, in particular macroangiopathy.