C-peptide
Measurement Errors in Determining Type 1 or Type
2 Diabetes
Errors are likely to result when diagnosing type
1 or 2 diabetes based on a measurement of basal
fasting C-peptide (CP), and 6-minute post-glucagon-stimulated
C-peptide (CPS).
Lead
author Farhad Zangeneh, MD, Mayo Clinic and Mayo
Medical School, Rochester, Minn, reported the
finding here on May 16th at the American Association
of Clinical Endocrinologists 12th Annual Meeting
and Clinical Congress.
Using
data gathered from the population-based Rochester
Diabetic Neuropathy Study, Dr. Zangeneh's team
followed 317 patients with diabetes who participated
in a longitudinal follow-up study for a mean duration
of 7.1 years (range 1.9 to 16.4 years).
CP
and CPS averaged 0.58 and 1.06 nmol/L at the beginning
of the study, and decreased to 0.41 and 0.71 nmol/L
respectively by its end. "[During the course
of the investigation], considerable variability
was noted among individual study subjects,"
stated Dr. Zangeneh.
Eighteen
study patients had CP or CPS increment measurements
(CPI) less than 0.17 or 0.07 nmol/L on at least
one occasion, while 3 of the 16 patients, on subsequent
follow-up visits, had CPI values greater than
those thresholds.
"Despite
the variability, there is insulin-production decline
over time, so the data reaffirm the [homeostasis
model assessment] of insulin decline. But since
the decrease does not occur in all patients, and
since it is highly variable, errors are likely
to result when a single measurement of fasting
CP and CPS is used to distinguish between type
1 and type 2 diabetes," said Dr. Zangeneh.
C-peptide
increment has long been used as surrogate markers
to estimate insulin secretion and to distinguish
between type 1 and type 2 diabetes.
AACE:[Study
title: The Natural History of Insulin Secretion
in Patients With Type 2 Diabetes. Abstract 65]
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FACT:
For each risk factor present, the risk of cardiovascular
death is about three times
greater in people with diabetes as compared to
people without the condition. IDF
.
