"Brittle" diabetes, also known as unstable diabetes or labile diabetes, is a term that was traditionally used to describe the dramatic and recurrent swings in glucose levels, often occurring for no apparent reason in insulin-dependent diabetes. This term, however, has no biologic basis and should not be used. Still, type 1 diabetes can be accompanied by irregular and unpredictable high blood sugar levels, frequently with ketosis, and sometimes with serious low blood sugar levels. Other complications include an impaired counterregulatory response to low blood sugar, infection, gastroparesis (which leads to erratic absorption of dietary carbohydrates), and endocrinopathies (e.g., Addison's disease). These phenomena are believed to occur no more frequently than in 1% to 2% of persons with type 1 diabetes.
Autonomic changes involving cardiovascular control (eg, heart rate, postural responses) have been described in as many as 40% of children with diabetes. Cardiovascular control changes become more likely with increasing duration and worsening control.  In a study by 253 patients with type 1 diabetes (mean age at baseline 14.4 y), Cho et al reported that the prevalence of cardiac autonomic dysfunction increases in association with higher body mass index and central adiposity. 
Long-term complications arise from the damaging effects of prolonged hyperglycemia and other metabolic consequences of insulin deficiency on various tissues. Although long-term complications are rare in childhood, maintaining good control of diabetes is important to prevent complications from developing in later life.  The likelihood of developing complications appears to depend on the interaction of factors such as metabolic control, genetic susceptibility, lifestyle (eg, smoking, diet, exercise), pubertal status, and gender. [40, 41] Long-term complications include the following: