Abstract

The markers of microvascular complications of type 1 diabetes were evaluated in adolescents in a cross sectional survey of 100 out of 138 eligible patients aged 9-19 years with a duration of diabetes over two years who visited the Paediatric Outpatient Clinic at Oulu University Hospital in 1997-1999, and one hundred healthy controls.

Two patients in early or mid-puberty had non-proliferative diabetic retinopathy, but no other signs of microvascular complications.

The five patients with persistent microalbuminuria were all girls; one prepubertal, one late pubertal and three postpubertal. Their mean glycated haemoglobin A1c (HbA1c) was higher, but they had a similar duration of diabetes and age distribution to those without microalbuminuria.

The adolescent patients were predisposed to higher fasting serum total and low-density lipoprotein cholesterol and triglyceride levels and higher diastolic blood pressure than the control subjects. The proportional total body fat was highest in the girls with diabetes by the end of puberty, while serum leptin levels did not differ between the patients and healthy controls. The patients had low fasting serum insulin levels and high insulin-like growth factor-binding protein 1 levels, related to hypoinsulinaemia.

Distal motor nerve function in the lower extremities were already affected before puberty, and distal and proximal nerve function deteriorated as puberty advanced. Ten patients had neurophysiologically confirmed distal diabetic polyneuropathy, and they were older and they had longer duration of diabetes and higher HbA1c than patients without polyneuropathy.

Although cardiovascular function was in the main well preserved in the adolescents with type 1 diabetes, the power spectrum analysis of heart rate variability showed attenuated autonomic nervous system reactivity.

Taken together these data show that a relatively small proportion of adolescents with type 1 diabetes have signs of microvascular complications. The prevalences of diabetic retinopathy, persistent microalbuminuria and distal diabetic polyneuropathy were 2%, 6% and 10%, respectively. Pubertal maturation seems to promote the progression of early signs of microvascular complications in patients affected by type 1 diabetes.