Abstract
C-peptide immunoreactivity in 24 hour-urine specimens from diabetic patients was assayed, and insulin dependent and non-insulin dependent diabetes were compared.
The mean±SD of urinary C-peptide (UCPR pg/day) was 74.7±26.3 in healthy subjects, 72.7±28.1in diet-treated diabetics and 61.8±28.3 in sulfonylurea (SU)-treated patients.UCPR was almost always more than 30μg/day in diet-and SU-treated patients.In insulin-treated patients, the mean±SD of urinary CPR was 30.3±27.5, which was significantlyless than in the SU-treated group (p<0.01), but UCPR values were widely scattered from undetectable levels to the normal range.
Insulin-treated patients were subdivided according to the reasons for starting insulin treatment. In group A, the probable IDDM group, with a history of abrupt onset of diabetes or ketoacidosis, UCPR was definitely low (9.2±8.8), and the individual value was less than 20μg in almost all patients with duration of diabetes of more than one year.In group B, in which insulin treatment was started because of co-existing liver disease, severe diabeticcomplications or surgery, UCPR did not differ significantly from that in the SU-treated group.In group C, in which insulin was initiated because of onset of diabetes at a young age, severe emaciation orunresponsiveness to SU drugs, UCPR was intermediate between group A and group B.
In conclusion, urinary C-peptide seems to provide a good and convenient parameter for determining the degree of insulin dependency in diabetic patients.
