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Aims: To explore the factors mediating the relationship between body mass index (BMI) and diabetic retinopathy (DR) in Chinese type 2 diabetes patients. Methods: This is a cross-sectional study. Data of 2,533 patients with type 2 diabetes were studied from the Shanghai Diabetes Registry Database. DR was assessed using non-mydriatic fundus photography and graded as non-DR, mild-moderate (DR I-II), and sight-threatening (DR III-IV). BMI (kg/m) was classified as normal weight (18.5 ≤ BMI < 25), overweight (25 ≤ BMI < 30), and obese (BMI ≥ 30). β cell function was evaluated by fasting C-peptide (FCP). Results: DR was present in 701 (27.7 %) patients. Patients with DR had lower BMI (24.3 vs. 24.9 kg/m, P = 0.001) and fasting C-peptide (1.46 vs. 1.86 ng/ml, P < 0.001) than those without DR. The association between BMI (2 kg/m interval) and DR was U-shaped; patients with BMI 28-29.9 kg/m had the lowest DR rate. Compared with normal weight, overweight was associated with reduced risk of any DR [odds ratio (OR) 0.73], DR I-II (OR 0.76), and DR III-IV (OR 0.64) after adjustment for sex, age at diabetes diagnosis, and duration of diabetes. This negative association attenuated after adjustment for other confounders and became nonsignificant after further adjustment for FCP. Patients with different BMI categories had similar DR risk when stratified by FCP tertiles. Conclusion: Overweight patients have lower DR prevalence than normal weight individuals, which may be attributable to better β cell function in overweight patients. [ABSTRACT FROM AUTHOR]

A cohort of 82 patients with Type 1 (insulin-dependent) diabetes was followed prospectively for 24 months, and 54 of them for 30 months, to study the relationship between fasting levels of immunoreactive C-peptide and titres of islet cell antibodies. After diagnosis, fasting C-peptide rose temporarily for 1-6 months of insulin therapy and declined continuously thereafter. While islet cell antibodies were present among 55% of the newly diagnosed patients, only 31% remained positive at 30 months. Their antibody titres decreased from 1∶81 at diagnosis to 1∶3. Only 3 patients (4%) who were islet cell antibody negative at diagnosis became positive later. The median C-peptide values among the persistently islet cell antibody positive patients decreased from 0.11 pmol/ml at 18 months, to 0.09 pmol/ml at 24 months, to 0.06 pmol/ml at 30 months compared to 0.18 ( p=0.04), 0.15 ( p=0.05) and 0.16 ( p< 0.003) pmol/ml, respectively, for the islet cell antibody negative patients. The median slope for the latter was −0.09 compared to −0.19 for the islet cell antibody positive patients ( p=0.01). These differences were reflected in increasing dosages of insulin, since patients remaining antibody-positive for 30 months were given 1.3-1.4 times more insulin ( p=0.01-0.004) than the antibody negative patients. This study demonstrates that islet cell antibodies may be a useful marker for predicting an increased rate by which endogenous B cell function is lost in Type 1 diabetes. [ABSTRACT FROM AUTHOR]

To clarify the utility of islet cell antibodies (ICA) to correctly classify and predict insulin treatment in newly diagnosed diabetic subjects, ICA, body mass index (BMI), glycated hemoglobin (HbA), and fasting plasma C-peptide values were evaluated at and 3 years after diagnosis in 233 new, consecutively diagnosed, adult diabetic patients classified as obese or nonobese (National Diabetes Data Group, NDDG criteria). Among the 233 patients, 31 were nonobese ICA-positive (mean age at diagnosis 43±3 years), 55 nonobese ICA-negative (mean age at diagnosis 58±2 years), 7 obese ICA-positive (mean age at diagnosis 57±5 years), and 139 obese ICA-negative (mean age at diagnosis 58±1 years). Fasting C-peptide decreased ( P<0.05) in nonobese ICA-positive patients who after 3 years showed lower BMI (22.6±0.6 versus 24.5±0.4; P<0.05), lower fasting C-peptide (0.14±0.06 nmol/l versus 0.71±0.07 nmol/l; P<0.001), and higher frequency of insulin treatment [28/31 (90%) versus 6/45 (13%); P<0.001] than nonobese ICA-negative patients. In obese ICA-positive patients, fasting C-peptide also decreased (Δ C-peptide 0.17±0.04 nmol/l; P<0.05) after diagnosis, and 3 years after diagnosis, obese ICA-positive patients showed lower BMI (25.7±1.2 versus 29.8±0.4; P<0.01) and fasting C-peptide (0.08±0.04 nmol/l versus 1.06±0.05 nmol/l; P<0.001) and higher HbA values (9.92%±0.68% versus 7.39%±0.21%; P<0.01) and a higher frequency of insulin treatment [7/7 (100%) versus 5/121 (4%); P<0.001] than obese ICA-negative patients. Therefore, ICA detected at diagnosis of diabetes in both obese and nonobese adult patients indicate β-cell dysfunction, high HbA levels, and progression to insulin dependency. [ABSTRACT FROM AUTHOR]