Presence of autoimmunity to pancreatic antigens in a patient with fibrocalculous pancreatic diabetes

Fibrocalculous pancreatic diabetes (FCPD)

Fibrocalculous pancreatic diabetes (FCPD) is an uncommon form of diabetes that occurs as a result of chronic calcific pancreatitis, in the absence of alcohol abuse. The disease is restricted to tropical regions of the world, and southern India has the highest known prevalence of FCPD. The typical patient with FCPD is a lean adolescent or young adult of either sex, presenting with history of recurrent bouts of abdominal pain and steatorrhea. Demonstration of large, discrete pancreatic calculi by plain radiographs or ultrasonography of the abdomen is diagnostic. While the exact etiology of FCPD is unknown, genetic, nutritional and inflammatory factors have been hypothesized to play a role. Diabetes in FCPD is often brittle and difficult to control; most patients require multiple doses of insulin for control of glycemia. However, in spite of high blood glucose levels, patients rarely develop ketosis. Malabsorption responds to pancreatic enzyme supplementation. Surgical removal of stones is indicated for symptomatic relief of intractable pain. While patients with FCPD develop microvascular complications as frequently as those with type 2 diabetes, macrovascular disease is uncommon. Development of pancreatic malignancy is the most dreaded complication and should be suspected in any patient who complains of weight loss, back pain or jaundice.

The islet autoantibody titres: their clinical relevance in latent autoimmune diabetes in adults (LADA) and the classification of diabetes mellitus

Latent autoimmune diabetes in the adult (LADA) is a slowly progressive form of autoimmune diabetes, characterized by diabetes-associated autoantibody positivity. A recent hypothesis proposes that LADA consists of a heterogeneous population, wherein several subgroups can be identified based on their autoimmune status. A systematic review of the literature was carried out to appraise whether the clinical characteristics of LADA patients correlate with the titre and numbers of diabetes-associated autoantibodies. We found that the simultaneous presence of multiple autoantibodies and/or a high-titre anti-glutamic acid decarboxylase (GAD)--compared with single and low-titre autoantibody--is associated with an early age of onset, low fasting C-peptide values as a marker of reduced pancreatic B-cell function, a high predictive value for future insulin requirement, the presence of other autoimmune disorders, a low prevalence of markers of the metabolic syndrome including high body mass index, hypertension and dyslipidaemia, and a high prevalence of the genotype known to increase the risk of Type 1 diabetes. We propose a more continuous classification of diabetes mellitus, based on the finding that the clinical characteristics gradually change from classic Type 1 diabetes to LADA and finally to Type 2 diabetes. Future studies should focus on determining optimal cut-off points of anti-GAD for differentiating clinically relevant diabetes mellitus subgroups.

Role of islet autoimmunity in the aetiology of different clinical subtypes of diabetes mellitus in young north Indians

AIMS

To determine the role of islet autoimmunity in the aetiology of different clinical subtypes of diabetes mellitus in young north Indian patients by measuring islet autoantibodies.

METHODS

In a cross-sectional study, 145 young patients with diabetes (onset < 30 years) were subdivided into the following categories: Type 1 diabetes (n = 83), malnutrition-modulated diabetes mellitus (MMDM, n = 31) and fibro-calculous pancreatic diabetes (FCPD, n = 31). MMDM subjects presented with emaciation and severe insulin-requiring but ketosis-resistant diabetes, while FCPD was associated with idiopathic chronic calcific pancreatitis. Antibodies to glutamic acid decarboxylase (GADA) and IA-2 (IA-2 A) were detected by immunoprecipitation of 35S-labelled recombinant antigens and cytoplasmic islet cell antibody (ICA) by indirect immunofluorescence.

RESULTS

GADA were present in a significant proportion (23%) of patients with MMDM. In contrast, IA-2 A was increased only among patients with Type 1 diabetes (22%), but not MMDM (3%, P < 0.05). Among patients with a duration of diabetes < 2 years, GADA and/or IA-2 A were found in 61% of Type 1 diabetic and 37% of MMDM patients (P < 0.01). MMDM patients who were positive for GADA had a shorter duration of diabetes, but did not differ in their age at onset of diabetes, body mass index, fasting plasma C-peptide, or frequency of thyroid microsomal and parietal cell antibodies. FCPD subjects had the lowest prevalence of autoantibodies: IA-2 and ICA were absent, while GADA were present in 7% (P < 0.05 vs. Type 1 diabetes).

CONCLUSIONS

GADA, though not IA-2 A, were present in a substantial proportion of patients with the MMDM variant of diabetes, suggesting that islet autoimmunity may play a role in its pathogenesis. In contrast, none of the islet antibodies was increased in subjects with FCPD, making it likely that it is a secondary type of diabetes.

Type 1 1/2 diabetes: myth or reality?

The disease process in classical Type 1 diabetes patients (IDDM) is believed to be autoimmune. In contrast, the disease process in classical Type 2 diabetes patients (NIDDM) is not autoimmune and a decreased sensitivity to insulin action is the main abnormality. The clinical distinction of Type 1 diabetes versus Type 2 diabetes is recognized to be imperfect and has limitations. There is a group of individuals (Type 1 1/2 diabetes), who present like typical NIDDM, but have some of the immunological and clinical features of IDDM. We review the current medical literature on Type 1 1/2 diabetes with special reference to its clinical characteristics, natural history and pathophysiology. Since the distinction between these two forms of diabetes may have important therapeutic implications especially with regards to the benefits of insulin therapy in patients with Type 1 1/2 diabetes and because of the need for uniformity in its diagnosis we recommend that both clinical plus biochemical criteria (the presence of ICA and/or GAD Ab, HLA typing and tests to quantify beta cell function) be used to make a diagnosis. Comparative studies in the area of cytokine production, T cell reactivity and autoantibody clustering between classic Type 1 diabetes and Type 1 1/2 diabetes patients are needed as are studies with the animal model of Type 1 1/2 diabetes, Psammomys obesus.

Islet-cell antibodies in malnutrition-related diabetes mellitus from north India

The etiology of malnutrition-related diabetes mellitus (MRDM)--protein-deficient pancreatic diabetes (PDPD) and fibro-calculous pancreatic diabetes (FCPD)-is unclear. We studied the role of autoimmunity against pancreatic islet cells in the etiology of these two subtypes of MRDM by measuring islet-cell antibodies (ICA) in 23 patients with PDPD, 25 with FCPD and 62 with Type 1 diabetes. Three patients (13%) with PDPD had detectable ICA. Including a patient with a high titre of ICA (> 80 JDF units). The frequency of ICA in patients with PDPD was significantly lower than subjects with Type 1 diabetes (22/62, 35%; P < 0.05). Among patients studied at onset. ICA prevalence was lower in the PDPD patients (1/7, 14%) compared to subjects with Type 1 diabetes (8/20, 40%). No patient of FCPD had detectable ICA (P < 0.001 vs. Type 1 diabetes subjects). We conclude that autoimmunity may play a role in the etiology of some patients with the PDPD subtype of MRDM. However, FCPD is unlikely to have an autoimmune etiology.

Comparison of anti-human insulin antibodies detection by commercial enzyme-linked immunosorbent assay kit, displacement enzyme-linked immunosorbent assay and radioimmunoassay, in Thai diabetic patients

Antibodies specific to human insulin, in sera of Thai diabetic patients and normal healthy individuals, were detected by a commercial enzyme-linked immunosorbent assay (ELISA) kit, displacement ELISA and radioimmunoassay (RIA). Among 36 insulin-treated patients, the antibodies were detected in 22, 23 and 20 individuals, by RIA, commercial ELISA kit and displacement ELISA, respectively. Among those who had never previously received insulin therapy, RIA showed positive results in 5/11 patients with insulin-dependent diabetes mellitus (IDDM) and 1/2 patients with fibrocalculous pancreatic diabetes (FCPD); but were negative in all 26 patients with non-insulin-dependent diabetes mellitus (NIDDM) and 30 normal healthy individuals. The commercial ELISA kit could detect such insulin autoantibodies (IAA) in 4/11 IDDM, 3/26 NIDDM, 2/2 FCPD patients and 4/30 normal controls; while the displacement ELISA showed positive IAA detection in 5/11 IDDM, 2/26 NIDDM, 2/2 FCPD and 2/30 normal controls. By using RIA as the 'gold standard', the commercial ELISA kit had 92.86% sensitivity, 87.01% specificity, 88.57% accuracy, 72.22% positive predictive value and 97.10% negative predictive value; while these indices for the displacement ELISA were 85.71%, 90.01%, 89.52%, 77.42% and 94.59%, respectively.