Göran Sundkvist

Quantitative assay using recombinant human islet glutamic acid decarboxylase (GAD65) shows that 64K autoantibody positivity at onset predicts diabetes type.

At and before onset, most insulin-dependent diabetics (IDDM) have islet GAD65 autoantibodies (GAD65Ab). Since IDDM also occurs in older patients where non-insulin-dependent diabetes is common, we studied GAD65Ab at onset to classify diabetes type. Our quantitative immunoprecipitation assay uses recombinant human islet GAD65 stably expressed in hamster fibroblasts. Electrophoretic mobility was identical to native islet GAD65. Like native antigen, recombinant GAD65 migrated as two bands during electrophoresis, but converted to one under stronger reduction. Immunoprecipitation was linear with respect to antibody or antigen concentration. In 120 population-based diabetic patients of all ages grouped by treatment at onset and after 18 mo, GAD65Ab were present in 70% on insulin (n = 37), 10% on oral agent (n = 62, P < 0.0001), 69% changing from oral agent to insulin (n = 16, P < 0.001), and 1 of 33 controls. 65% with GAD65Ab, versus 8% without, changed from oral agent to insulin (P < 0.01). The GAD65Ab quantitative index was remarkably stable, and only 2 of 32 patients changed antibody status during follow-up. Concordance between GAD65Ab and islet cell antibodies was 93%. Quantitative correlation was approximate but significant. This highly sensitive, quantitative, high capacity assay for GAD65Ab reveals treatment requirements better than clinical criteria, perhaps guiding immunomodulatory therapy.

Islet cell and other organ-specific autoantibodies in all children developing Type 1 (insulin-dependent) diabetes mellitus in Sweden during one year and in matched control children

SummaryThe majority (about 90%) of children developing Type 1 (insulin-dependent) diabetes mellitus do not have a first-degree relative with the disease. Nearly all (389/405, 96%) children (0–14 years) in Sweden, who developed diabetes during one year, were therefore studied to compare islet cell, thyroid peroxidase, thyroglobulin, and gastric H+, K+-ATPase antibodies with 321 age, sex, and geographically matched, but non-related, control children. Islet cell (cytoplasmic) antibodies were found in 81% (316/389) of the patients and in 3% (9/321) of the control children (p<0.001). The median islet cell antibody levels were 70 (range 3–8200) Juvenile Diabetes Foundation (JDF) Units in the islet cell antibody positive patients, and 27 (range 17–1200) JDF Units in the control children (NS). Autoantibodies against thyroid peroxidase (8%), thyroglobulin (6%), and gastric H+, K+- ATPase (3%) were all increased in the patients compared with the control children, being 2% (p<0.001), 2% (p<0.01), and 0.3% (p<0.01), respectively. During an observation time of 20–34 months, two of the nine islet cell antibody positive control children developed Type 1 diabetes, after 8 and 25 months respectively, while the others remained healthy and became islet cell antibody negative. None of the islet cell antibody negative control children developed diabetes during the same time of observation. This first investigation of an unselected population of diabetic children and matched control children shows: that islet cell antibodies are strongly associated with newly diagnosed childhood diabetes, that other autoantibodies are more frequent among diabetic children than control children, and that the frequency of islet cell antibodies in the background population of children is higher than previously documented, and could also be transient, underlining that factors additional to islet cell antibodies are necessary for the later development of Type 1 diabetes.

Autonomic vagal nerve dysfunction in patients with ulcerative colitis

Autonomic nerve function was evaluated in 40 patients with total ulcerative colitis and in 25 patients with irritable bowel syndrome by three established non-invasive tests based on the heart reactions to deep breathing (E/I ratio) and tilt (acceleration and brake index). None of the patients were diabetic. Most of the patients with ulcerative colitis were clinically and biochemically inactive; 10 had previously undergone colectomy. The results were compared with a control group consisting of 56 healthy individuals and 33 previously investigated patients with Crohns disease, 45% of whom demonstrated autonomic neuropathy (AN). Patients with ulcerative colitis had a significantly lower E/I ratio than controls in age-corrected values, indicating vagal nerve dysfunction. Altogether, 35% had signs of AN. In patients with irritable bowel syndrome 36% had evidence of AN, a figure in agreement with observations from other investigators. We conclude that AN is common in patients with ulcerative colitis, regardless of disease activity and previous colectomy. In contrast to a predominantly sympathetic dysfunction in Crohns disease, AN in ulcerative colitis was vagal.

Predictive value of islet cell and insulin autoantibodies for Type 1 (insulin-dependent) diabetes mellitus in a population-based study of newly-diagnosed diabetic and matched control children

SummaryMost studies evaluating immune markers for prediction of Type 1 (insulin-dependent) diabetes mellitus have focused on first degree relatives, although only 10 % of newly-diagnosed patients have an affected first degree relative. The Swedish Childhood Diabetes Register identifies 99 % of all diabetic children at diagnosis. In this population-based study, islet cell antibodies and insulin autoantibodies in 0–14-year-old Swedish consecutively-diagnosed patients and control subjects were analysed to define their sensitivity and specificity. Over 16 months (1986–1987), 515 Swedish children developed diabetes. Plasma samples were obtained from 494 (96 %) patients, and 420 matched control children. Among patients, the frequency of islet cell antibodies was 84 % (415 of 494), insulin autoantibodies 43 % (145 of 334); 40 % (135 of 334) were positive for both and 88 % (294 of 334) were positive for one or both. Among control children, 3 % (14 of 420) had islet cell antibodies, 1 % (4 of 390) insulin autoantibodies, and 4 % (16 of 390) had either autoantibody marker. The predictive value of finding a patient with the disease was only 7% since 4 % of the control children were antibody-positive and the cumulative incidence rate up to 15 years of age is 0.38 %. None of the autoantibody-positive (n = 21) or negative control children developed diabetes during 3 to 5 years of follow-up. Longitudinal investigations of islet cell or insulin-autoantibody-positive healthy children are necessary to accurately determine the conversion rate from marker positivity to disease onset.

β-Cell Function in Relation to Islet Cell Antibodies During the First 3 Yr After Clinical Diagnosis of Diabetes in Type II Diabetic Patients

OBJECTIVE— To determine the effects of islet cell antibodies on β-cell function during the first 3 yr after diagnosis in type II diabetic patients. RESEARCH DESIGN AND METHODS— β-cell function in type II diabetic patients with (n = 11, 50 ± 5 yr of age) and without (n = 10, 52 ± 4 yr of age) ICA was followed prospectively and compared with β-cell function in type I adult diabetic patients (n = 17, 37 ± 5 yr of age) and in healthy control subjects (n = 34, age 45 ± 3 yr). β-cell function was evaluated as fasting C-peptide, 1 + 3 min C-peptide after intravenous glucose, and ∆ C-peptide after glucagon. RESULTS— Fasting C-peptide was equal in type II diabetic patients with ICA (0.30 ± 0.03 nM) and type I diabetic patients (0.24 ± 0.03 nM) at diagnosis, and decreased (P < 0.05) during 3 yr in these groups but not in type II diabetic patients without ICA. At diagnosis, type II diabetic patients with ICA showed a 1 + 3 min C-peptide (0.92 ± 0.17 nM) lower (P < 0.001) than control subjects but higher (P < 0.05) than type I diabetic patients (0.53 ± 0.11 nM). After 1 yr, 1 + 3 min C-peptide in type II diabetic patients with ICA had decreased (P < 0.05) to 0.18 ± 0.11 nM and was equal to type I diabetic patients (0.38 ± 0.10 nM). ∆ C-peptide after glucagon was equally impaired in type II diabetic patients with ICA (0.38 ± 0.06 nM) and type I diabetic patients (0.35 ± 0.11 nM) at diagnosis. After 3 yr, type II diabetic patients with ICA had fasting C-peptide of 0.09 ± 0.04 nM, 1 + 3 min C-peptide of 0.18 ± 0.10 nM, and ∆ C-peptide after glucagon of 0.20 ± 0.09 nM, values equal to type I diabetic patients but lower (P < 0.01) than in type II diabetic patients without ICA, whose values remained unchanged; fasting C-peptide of 0.97 ± 0.17 nM, 1 + 3 min C-peptide of 2.31 ± 0.50 nM, and ∆ C-peptide after glucagon of 1.76 ± 0.28 nM. CONCLUSIONS— In patients considered type II diabetic with ICA, β-cell function progressively decreased after diagnosis, and after 3 yr was similar to type I diabetic patients, whereas β-cell function in type II diabetic patients without ICA was unchanged.

Islet Cell and Thyrogastric Antibodies in 633 Consecutive 15- to 34-Yr-Old Patients in the Diabetes Incidence Study in Sweden

The effect of age on ICA and thyrogastric antibodies at diagnosis of IDDM was evaluated in 633 consecutively diagnosed Swedish diabetic patients aged 15–34 yr and in 282 volunteers of the same age. ICAs were present in 61% (383 of 633) of the patients and in 2% (5 of 282) of control subjects. When the initial classification was considered, ICAs were detected in 69% (327 of 473) of patients with IDDM, 23% (19 of 83) of those with NIDDM, 50% (36 of 72) of those with unclassifiable diabetes, and 20% (1 of 5) of those with secondary diabetes. The frequency of ICA fell significantly (P < 0.001) with age in IDDM patients from 77% (104/135) in those 15–19 yr old to 52% (50 of 96) in 30- to 34-yr-old IDDM patients. The low frequency of ICA in 30- to 34-yr-old IDDM patients was confined to men (42%, 28 of 66). The frequency of gastric (H+, K+-ATPase) antibodies was significantly (P < 0.05) higher in IDDM patients (10%, 47 of 449) than in patients with NIDDM (3%, 3 of 80) and unclassifiable diabetes (4%, 3 of 72). In conclusion, the frequency of ICA at the diagnosis of IDDM in young adult subjects decreases with increasing age, particularly in men. The frequent finding of ICA in patients considered to have NIDDM or unclassifiable diabetes indicates that misclassification of diabetes is frequent in young adult patients recently diagnosed with diabetes.

Prolonged incubation in the two-colour immunofluorescence test increases the prevalence and titres of islet cell antibodies in Type 1 (insulin-dependent) diabetes mellitus

SummaryThe conventional indirect immunofluorescence test of islet cell antibodies was recently improved by the development of a two-colour immunofluorescence assay using a monoclonal proinsulin antibody to detect islet B cells. The aim of this study was to test whether in this new assay the prevalence and titre of ICA were affected by the time of incubation carried out in the presence of aprotinin (Trasylol) as an inhibitor of proteolysis. The end-point titre of ICA was therefore determined in sera from 70 children aged 0.6 to 15 years with recent onset Type 1 (insulin-dependent) diabetes mellitus, 50 healthy control subjects and 97 non-diabetic siblings of Type 1 diabetic children. In the conventional twocolour assay, ICA was positive in 53/70 (76%) Type 1 diabetic patients, 1/50 control subjects and 2/97 siblings after 30 min incubation. Prolonged incubation for 18 h increased the prevalence of ICA positive samples to 62/70 (89%) in the diabetic patients and to 2/50 in the control subjects, while the prevalence among the siblings was unchanged. Of the ICA positive non-diabetic subjects, one control child has a father with Type 1 diabetes, and one of the siblings subsequently developed Type 1 diabetes. In the diabetic patients the median titre was 1:32 for the 30 min incubation, and it increased to 1:64 for the 18 h incubation (p<0.001). A marked prozone effect was seen; 16% of the samples from the Type 1 diabetic children sera were negative at a 1:2 dilution, but were found positive at higher dilutions. In conclusion, an 18 h incubation increases the end point titres and the prevalence of ICA in the two-colour ICA assay in Type 1 diabetic children of recent onset. The prevalence and levels of ICA among these patients may be larger than hitherto expected.

Abnormal diastolic blood pressure and heart rate reactions to tilting in diabetes mellitus

SummaryThe orthostatic reaction to tilting was studied in 46 diabetics without symptoms of autonomic neuropathy and in 31 age-matched healthy control subjects. After tilting, the diastolic blood pressure rose in the control subjects but was unchanged or tended to fall in the diabetics, except in those of short duration without retinopathy. After tilting, the control subjects showed an immediate increase in heart rate with the highest value at 8.4±1.0 s (mean±SEM), followed by a transient decrease with lowest value at 21.2±0.9 s. The acceleration and brake index measured the changes in heart rate. The brake index was lower in diabetics of short duration with retinopathy (6.9±1.6) than in those without (14.4±2.3, p <0.01) as well as matched control subjects (18.7±2.5, p < 0.01). In the diabetics of long duration no differences were shown between those with or without retinopathy but the acceleration (10.3±1.6 vs 19.9±2.3, p < 0.05) and the brake index (5.3±1.4 vs 19.9±2.3, p < 0.01) were lower in those with vagal neuropathy.

Disturbed Autonomic Nerve Function in Patients with Crohn's Disease

Autonomic nerve function was evaluated in 33 patients with Crohns disease (age range, 19-66 years; mean, 36 years) by three established non-invasive tests based on the heart reactions to deep breathing (E/I ratio) and to tilt (acceleration and brake indices). Peripheral nerve function was evaluated neurographically and by measuring thresholds to vibration and temperature changes. None of the patients were diabetic, and all had normal thyroid function. In spite of normal peripheral nerve function, almost half of the patients, 48% (16/33), showed signs of autonomic neuropathy (AN). The occurrence of AN was not related to duration or severity of Crohns disease or to biochemical evidence of inflammation or malabsorption of vitamins and trace elements. We conclude that autonomic nerve dysfunction is a feature of Crohns disease which may be relevant with regard to the frequent disturbance in bowel function in patients with this disorder.

Islet cell antibodies and fasting C-peptide predict insulin requirement at diagnosis of diabetes mellitus

SummaryThe differential diagnosis between Type 1 (insulin-dependent) and Type 2 (non-insulin-dependent) diabetes is complicated since no specific markers are available for either disease. In this study, 244 consecutive patients were diagnosed with diabetes mellitus during two years in Malmö (230000 inhabitants), corresponding to an incidence rate of 53·100000−1·year−1. Age, body mass index, HbA1c, C-peptide, and levels of islet cell antibodies were determined at the clinical onset, and related to the classification at diagnosis and at follow-up (n=233) after a median time of 31 (range 1–49) months. After diagnosis, 42 of 244 (17%) were started on insulin while 202 of 244 (83%) were not. Islet cell antibodies were present in 25 of 42 (60%), and in 18 of 183 (10%), respectively. In the non-insulin treated group, patients with islet cell antibodies had lower body mass index (p<0.001), higher HbA1c (p<0.004), and lower C-peptide (p<0.001) than patients without. At follow-up, 11 of 18 (61%) islet cell positive patients were changed to insulin treatment, as were six other patients. Insulin was discontinued in five initially insulin-treated but islet cell antibody negative patients. The sensitivity, specificity and predictive value for insulin treatment at follow-up were for islet cell antibody positivity; 72%, 96% and 84%, respectively, and for low C-peptide value; 60%, 96%, and 80%, respectively. Islet cell antibodies and low C-peptide at diagnosis of diabetes mellitus are concluded to be useful markers to predict insulin dependence.