The use of 1.5-anhydroglucitol for monitoring glycemic control in islet transplant recipients.

We evaluated whether 1,5-anhydroglucitol (1,5-AG) (GlycoMark(®)), a test for measuring postprandial glucose and glucose variability, could be a tool for assessing short-term glycemic control in islet cell transplant (ICT) subjects. Data of 21 subjects, with type 1 DM and allogenic islet transplantation, who had concomitant fructosamine, HbA1c, 1,5-AG (n = 85 samples), and capillary glucose self-monitoring measurements (n = 2,979) were analyzed retrospectively at different time points after ICT. A significant negative association was observed between 1,5-AG and HbA1c (p = 0.02), but not with fructosamine. When HbA1c was divided in quartiles as <5.6, 5.6-5.9, 5.9-6.2, and >6.2, a decrease of an estimated 0.70 ± 0.30 µg/ml in 1,5-AG was associated with each quartile of increase in HbA1c (p < 0.0001). There was a significant decline of 1.64 ± 0.3mg/dl in postprandial glucose values for each 1 unit increase in 1,5-AG (p < 0.0001). For those with HbA1c ≥ 6.0% when 1,5-AG was ≥8.15 µg/ml, the mean estimated glucose level was 103.71 ± 3.66 mg/dl, whereas it was 132.12 ± 3.71 mg/dl when 1,5-AG was <8.15 µg/ml. The glucose variability (Glumax - Glumin) in subjects with 1,5-AG <8.15 µg/ml was 46.23 mg/dl greater than the subjects with 1,5-AG ≥8.15 µg/ml (HbA1c ≥ 6.0%). There was no significant association between GlycoMark and glucose variability where HbA1c < 6%. 1,5-AG significantly associated with postprandial glucose levels and glucose variability in ICT recipients with near-normal HbA1c (6.0-6.5%) levels. These findings suggest that 1,5-AG can be used to differentiate those ICT subjects with higher glucose variability despite having near-normal HbA1c. However, prospective studies are needed to evaluate the association between GlycoMark levels and the parameters of graft dysfunction/failure.

Liver fat accumulation after islet transplantation and graft survival.

Our objective is to evaluate if there is an association between liver fat accumulation after islet transplantation (ITx) and graft survival. A cohort study was conducted in 34 subjects with type 1 diabetes postallogeneic ITx. Liver fat content was evaluated by magnetic resonance imaging (MRI) (change in liver signal intensity on in-phase and opposed-phase images). Kaplan-Meier curves and Cox regression analysis were performed with islet dysfunction duration as the dependent variable and fat liver content as an independent one. Values of p < 0.05 were significant (SSPS(®)18.0 and MedCalc(®)12.5). Patients' mean age was 40 ± 8 years (diabetes duration: 31 ± 12 years; male: 41%). Islet survival did not differ in patients without (51 months, 95% CI 40-62 months) or with steatosis (48 months, 95% CI 38-58 months; p = 0.55) during islet dysfunction period. Nevertheless, survival curves appear to separate late in the follow-up, and after 40 months steatosis was associated with shorter graft survival (p log rank = 0.049). This association remained (RR 23.5, 95% CI 1.1-516.0; p = 0.045) after adjustments for possible confounding factors. In this sample of subjects with type 1 diabetes submitted to ITx, steatosis was not associated with islet failure in the whole cohort. However, in subjects with functional islets after 40 months, a shorter graft survival was observed in those with steatosis during the islet dysfunction period, even after adjustments to variables known to be associated with islet failure.