By Sue Mulley

HONG KONG (Reuters Health) - Young-onset type 2 diabetes is both clinically and aetiologically heterogeneous, according to findings from the ongoing Young Asian Patients with Newly Diagnosed Diabetes Mellitus (ASDIAB) study.

"The simple idea of type 1 and type 2 diabetes is no longer valid. We're seeing a whole range of different scenarios and complications," Dr. Clive S. Cockram, of the Chinese University of in Hong Kong, said in an interview with Reuters Health outside the Second Hong Kong Diabetes and Cardiovascular Risk Factors East Meets West symposium.

Consecutive patients aged 12 to 40 years are being recruited for this 5-year prospective but noninterventional study at centres in Hong Kong, Shanghai, Beijing, Chennai, Malaysia and Singapore. It was initiated in 1997 and has 2 more years to run. "This study is quite unique because we did not make any attempts to classify patients as type 1 or type 2 diabetics before the start," Dr. Cockram told Reuters Health.

He presented data on 919 of about 1000 patients recruited to date who have completed three study visits. The majority are aged 31 to 40, 66% are male and the mean body mass index is 25.2 kg/meters squared.

Only 45% of patients had diabetic parents. Forty-eight percent are being treated with oral hypoglycaemic agents, 18% with insulin, and 3% with insulin plus oral hypoglycaemic agents. The mean HbA1c and free plasma glucose values are 10.4% and 9.9 mmol/L, respectively.

"Only 19% had clear cut evidence of severe insulin deficiency as evidenced by C-peptide measurements before and after glucagon. Antibodies to glutamic acid decarboxylase were detected in 12%."

"Patients positive for antibodies to glutamic acid decarboxylase had a lower age at onset, a lower BMI than the negative patients and a lower rate of complications," Dr. Cockram said. "Some 62% of the glutamic acid decarboxylase antibody-positive patients were insulin deficient. Of the patients who were insulin sufficient, only 6% were glutamic acid decarboxylase antibody positive."

At the moment, the conventional wisdom is that complication rates depend on the severity of hyperglycaemia, duration of diabetes, presence of associated factors such as hypertension and possible genetic predisposition, Dr. Cockram noted.

"It may be that certain subtypes such as HNF-1-alpha [hepatocyte nuclear factor-1 alpha] gene mutations have additional susceptibility," he said, "but this is not known for certain, because the other factors can always be invoked to explain what is going on and additional effects of disease subtype may be difficult to dissect out."

"We have not yet analysed complication rates from the study patients and may not be able to answer the question when we do because of the fact that we are looking at newly presenting patients, and disease duration prior to diagnosis is likely to vary and may be shorter for the GAD-positive patients who are the most insulin deficient," Dr. Cockram told Reuters Health. He added that he and his colleagues have collected samples and are in the process of analysing gene polymorphisms.

(From Reuters Health)