[C-peptide].

OBJECTIVE: To investigate whether detectable C-peptide levels in type 1 diabetes is associated with a lower risk of diabetic ketoacidosis (DKA). RESEARCH DESIGN AND METHODS: We analyzed the Diabetes Control and Complications Trial publicly available data repository for the association between detectable stimulated C-peptide (>0.2 nmol/mL, measured annually) and DKA incidence over an average 6.5-year follow-up. We used crude and adjusted Andersen-Gill models for recurrent DKA events with time-dependent covariates. RESULTS: Of the 1,441 participants (53% male, median age 27 years), 129 (9%) experienced 180 DKA events. Of these events, 179 (99.44%) occurred after C-peptide was ≤0.2 nmol/L in the prior year and only 1 event occurred with C-peptide >0.2 nmol/L. C-peptide >0.2 nmol/L was associated with a DKA hazard ratio of 0.07 (95% CI 0.01-0.48; P = 0.007), consistent across adjusted models. CONCLUSIONS: Endogenous insulin production was significantly associated with lower DKA risk, suggesting that treatments preserving insulin production could decrease long-term DKA risk.

C-Peptide↗

PubMed1995

Successful simultaneous transplantation of kidney and fetal pancreatic islet masses.

This paper reports our experience with the successful simultaneous transplantation of kidney and fetal pancreatic islets in 46-year-old diabetic man. No detectable C-peptide level was noted and the end-stage nephropathy required hemodialysis. The cadaver kidney and two masses of 8-week-cultured fetal islets were grafted simultaneously. After revascularization of the kidney, the islet masses were placed under the kidney capsule. Following transplantation, islet function was demonstrated by a higher C-peptide level, which subsequently persisted. Twenty-four months after grafting, islet function was provoked by glucagon and glucose, which led to elevations in the C-peptide and insulin levels. The insulin requirement fell from 58 to 24 U/day during the post-transplant period of 24 months. The mean value of HbA1C (5.6% +/- 0.3%) indicated a constantly normal carbohydrate metabolism. Improvements in retinopathy were also noted. Three periods of kidney rejection were diagnosed, but these proved reversible with high-dose steroid treatment. The serum and urine beta-2-microglobulin levels correlated well with rejection and recovery. More than 2 years after grafting, kidney functions is in the normal range. On sonography, the transplanted islet masses were repeatedly clearly visible, and 24 months following transplantation the volume was twice the original one. The results indicate that simultaneous kidney and fetal pancreatic islet grafting is advantageous in end-stage nephropathy secondary to type I diabetes mellitus.

C-Peptide↗

PubMed1995

Insulin inhibits its own secretion from isolated, perifused human pancreatic islets.

It is still a controversial question whether insulin suppresses its own secretion. We prepared pure human islets from three pancreases by collagenase digestion and density gradient purification. Aliquots of 200 islet equivalents (IE, 150-microns sized-islets) were sequentially perifused at 37 degrees C with 3.3 mmol/l glucose (3.3G, 40 min), 16.7 mmol/l glucose (16.7G, 30 min) and again 3.3G (30 min) after 24 h, 37 degrees C culture in CMRL 1066 medium with or without the addition of either 200 or 400 microU/ml human insulin in the incubation medium (6 replicates each). Insulin secretion was assessed by C-peptide (Cp) measurement in the perifusate. Without added insulin (C) and with 200 (Ins200) or 400 (Ins400) microU/ml added insulin, basal Cp release was 0.12 +/- 0.03, 0.14 +/- 0.02 and 0.14 +/- 0.04 ng/ml, respectively. At 16.7G, the first-phase secretion peak (expressed as Cp value) was significantly lower with Ins200 (0.47 +/- 0.13 ng/ml, P < 0.02) and Ins400 (0.68 +/- 0.15 ng/ml, P < 0.05) than C (0.83 +/- 0.15 ng/ml). The second-phase secretion peak was also significantly (P < 0.05) reduced with added insulin (Ins200: 0.47 +/- 0.08 ng/ml; Ins400: 0.45 +/- 0.07 ng/ml) than in its absence (C: 0.65 +/- 0.09 ng/ml). Accordingly, total Cp secretion was lower with Ins200 (10.6 +/- 2.3 ng/ml, P = 0.03) and Ins400 (11.8 +/- 2.3 ng/ml) than with C (16.0 +/- 2.2 ng/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

C-Peptide↗