Prediction of residual islet β-cell function in young patients with type 1 diabetes mellitus

Abstract

Objective To investigate the predictive factors of residual β-cell function in young patients with newly-diagnosed type 1 diabetes mellitus. Methods After an average follow-up of (35.1±13.8)months, a total of 110 young patients with type 1 diabetes mellitus were analyzed. At baseline and follow-up, oral glucose tolerance test(OGTT)and C-peptide release test were carried out, the levels of HbA1C, glutamic acid decarboxylase-antibody(GAD), and the genetic polymorphisms of human leukocyte antigen(HLA)-Ⅱ were detected. The patients were divided into two groups: high-residual β-cell function group(high-RBF group)and low-residual β-cell function group(low-RBF group), which were defined as stimulated C-peptide(Cmax)≥0.6 ng/ml and <0.6 ng/ml at endpoint, respectively. Logistic regression analyses were performed to explore the factors that influence long-term residual β-cell function. Results Compared with low-RBF group, Cmax levels were higher [(1.87±1.35 vs 0.23±0.19)ng/ml, P<0.01], HbA1C levels were lower [(7.00±1.69 vs 8.39±1.77)%, P < 0.01], insulin dosages were lower[(0.62±0.17 vs 0.79±0.17)IU·kg-1·d-1,P <0.01] in high-RBF group at endpoint. Logistic regression analysis suggested that factors including age of onset(years)[OR=0.82, 95%CI 0.73-0.92, P=0.001], higher HLA risk status(OR=4.73, 95%CI 1.28-17.52, P=0.020), female sex(OR=3.39, 95%CI 1.03-11.22, P=0.045), diabetic ketoacidosis history at onset(OR=8.71, 95%CI 2.31-32.83, P=0.001), and higher mean HbA1C levels(OR=2.46, 95%CI 1.47-4.11, P=0.001)were related to low residual β-cell function. Compared with mean HbA1C level during diabetes course, predicted probability value for the four baseline factors(diagnosis age, HLA risk status, gender, and diabetic ketoacidosis history)as the onset state of type 1 diabetes patients was higher[(OR=145.75, 95%CI 17.30-1 228.31, P<0.01)vs(OR=1.82, 95%CI 1.24-2.69, P=0.003)]. Conclusion Younger age of onset, female, higher HLA risk status, diabetic ketoacidosis history at onset and poor glycemic control during diabetes course were the predictive factors of low residual β-cell function in the development of the disease. Compared with mean HbA1C level during diabetes course, an onset state of type 1 diabetes mellitus patients is more valuable to predict long-term residual β-cell function. (Chin J Endocrinol Metab, 2016, 32: 728-733) Key words: Diabetes mellitus, type 1; Islet β-cell function; Human leukocyte antigen class Ⅱ; Prognosis