Islet cell antibodies are associated with beta-cell failure also in obese adult onset diabetic patients

Relationship between β-Cell Autoantibodies and Their Combination with Anthropometric and Metabolic Components and Microvascular Complications in Latent Autoimmune Diabetes in Adults

AIMS

Our study aimed to investigate the relationship between three autoantibodies and their combination with anthropometric and metabolic components and microvascular complications in patients with latent autoimmune diabetes in adults (LADA).

METHODS

Our study included 189 LADA patients divided into four subgroups according to the autoantibodies present: glutamic acid decarboxylase autoantibodies (GADA) only; zinc transporter-8 autoantibodies (ZnT8A)+GADA; insulinoma-associated-2 autoantibodies (IA-2)+GADA; and ZnT8+IA-2+GADA.

RESULTS

Compared to GADA positivity only, patients with ZnT8+GADA positivity and ZnT8+IA-2+GADA positivity had a shorter diabetes duration and lower body mass index (BMI); patients with ZnT8+GADA positivity were younger and showed an increase in glomerular filtration rate, while those with ZnT8+IA-2+GADA positivity had lower C-peptide and lower insulin resistance measured with HOMA2-IR. In a multiple regression analysis, ZnT8 positivity was associated with lower BMI (p = 0.0024), female sex (p = 0.0005), and shorter duration of disease (p = 0.0034), while IA-2 positivity was associated with lower C-peptide levels (p = 0.0034) and shorter diabetes duration (p = 0.02). No association between antibody positivity and microvascular complications of diabetes, including retinopathy, neuropathy, and microalbuminuria, as well as with variables of glucose control and β-cell function were found.

CONCLUSION

The results of our study suggest that ZnT8 and IA-2 autoantibodies are present in a significant number of LADA patients and associated with clinical and metabolic characteristics resembling classic type 1 diabetes. Due to increased LADA prevalence, earlier identification of patients requiring frequent monitoring with the earlier intensification of insulin therapy might be of special clinical interest.

Determination of autoantibodies in dogs with diabetes mellitus

Background and Aim:

The classification of diabetes mellitus (DM) in dogs has been controversial as currently canine insulin-dependent DM is classified together with absolute insulin deficiency, non-insulin-dependent DM, and relative insulin deficiency. Studies on human autoantibodies evaluated in canines with DM, such as anti-glutamic acid decarboxylase (GAD65), anti-islet antigen 2 (IA2), and anti-zinc transporter isoform 8 (ZnT8), have been inconclusive. Thus, this study was designed to establish the serological profile of anti-GAD65, anti-IA2, and anti-ZnT8 antibodies in a group of dogs with and without DM.

Materials and Methods:

Sixty-one dogs, including 31 patients with DM (with and without insulin treatment) and 30 patients without DM (normal weight and obese), were included for determining autoantibodies using a human enzyme-linked immunosorbent assay (ELISA) detection system for type 1 DM.

Results:

This study found the presence of anti-IA2 antibodies in 58% of the sample (18/31 patients with DM); however, the presence of anti-GAD65 was not detected, and anti-ZnT8 was found in 3 (9.6%) patients with DM.

Conclusion:

This study showed a higher positive frequency of anti-IA2 antibodies in a sample of canine with DM, indicating that alterations in the signaling vesicle tyrosine phosphatase 2 lead to lower insulin release and thus to an increase in patients’ glycemia. These preliminary results should be taken with caution and corroborated by a canine-specific assay when an ELISA is available for such determination.

Latent autoimmune diabetes of adulthood (LADA) is associated with small fibre neuropathy

AIM

To assess if latent autoimmune diabetes of adulthood (LADA) is associated with small fibre neuropathy.

METHODS

Participants with LADA (n=31), Type 2 diabetes (n=31) and healthy control participants without diabetes (n=31) underwent a detailed assessment of neurologic deficits, quantitative sensory testing, electrophysiology, skin biopsy and corneal confocal microscopy.

RESULTS

The groups were matched for age (healthy control without diabetes: 53.5±9.1 vs. Type 2 diabetes: 58.0±6.5 vs. LADA: 53.2±11.6 years), duration of diabetes (Type 2 diabetes: 10.0±8.3 vs. LADA: 11.0±9.1 years) and blood pressure. However, BMI (P=0.01) and triglycerides (P=0.0008) were lower and HbA_1c (P=0.0005), total cholesterol (P=0.01) and HDL (P=0.002) were higher in participants with LADA compared with Type 2 diabetes. Peroneal motor nerve conduction velocity (P=0.04) and sural sensory nerve conduction velocity (P=0.008) were lower in participants with latent autoimmune diabetes in adults compared with Type 2 diabetes. Intra-epidermal nerve fibre density (P=0.008), corneal nerve fibre density (P=0.003) and corneal nerve branch density (P=0.006) were significantly lower in participants with LADA compared with Type 2 diabetes. There were no significant differences in the other neuropathy parameters.

CONCLUSIONS

Despite comparable age and duration of diabetes, participants with LADA demonstrate more severe neuropathy and particularly small fibre neuropathy, compared with participants with Type 2 diabetes.

Relationship between autoantibodies combination, metabolic syndrome components and diabetic complications in autoimmune diabetes in adults

The aim of our study was to establish the possible association between double or triple antibody positivity and latent autoimmune diabetes (LADA) phenotype in the context of metabolic syndrome (MS) prevalence and its individual components. This cross-sectional study population comprised 69 islet cell antibody-positive patients coming for their comprehensive annual review. They were divided into three groups according to antibody positivity. Twenty-five (36.2 %) were male, mean age of 51 years with disease duration of 8 years. Twenty-eight (40.58 %) were positive only for GAD Abs, 26 (37.68 %) were positive for ICA and GAD Abs and 15 (21.74 %) were positive for GAD, ICA, and IA2 Abs. The lowest value of waist circumference, MS, and artherial hypertension prevalence was found in the group positive for all three antibodies. In the multinomial multivariate logistic regression model, MS was negatively associated with triple Abs positivity compared to single Ab positivity and double Abs positivity. Our results highlight the importance of inverse association between simultaneous Abs positivity for ICA, GAD, and IA2 with the MS and its components present in LADA patients. This inverse relationship might implicate that LADA patients are phenotypically closer to T1DM. The contribution of IA2 Ab positivity merits is to be considered in the determination of LADA phenotypes, while its diagnostic value needs to be clarified in future follow-up studies.

Islet autoimmunity identifies a unique pattern of impaired pancreatic beta-cell function, markedly reduced pancreatic beta cell mass and insulin resistance in clinically diagnosed type 2 diabetes

There is a paucity of literature describing metabolic and histological data in adult-onset autoimmune diabetes. This subgroup of diabetes mellitus affects at least 5% of clinically diagnosed type 2 diabetic patients (T2DM) and it is termed Latent Autoimmune Diabetes in Adults (LADA). We evaluated indexes of insulin secretion, metabolic assessment, and pancreatic pathology in clinically diagnosed T2DM patients with and without the presence of humoral islet autoimmunity (Ab). A total of 18 patients with at least 5-year duration of clinically diagnosed T2DM were evaluated in this study. In those subjects we assessed acute insulin responses to arginine, a glucose clamp study, whole-body fat mass and fat-free mass. We have also analyzed the pancreatic pathology of 15 T2DM and 43 control cadaveric donors, using pancreatic tissue obtained from all the T2DM organ donors available from the nPOD network through December 31, 2013. The presence of islet Ab correlated with severely impaired β-cell function as demonstrated by remarkably low acute insulin response to arginine (AIR) when compared to that of the Ab negative group. Glucose clamp studies indicated that both Ab positive and Ab negative patients exhibited peripheral insulin resistance in a similar fashion. Pathology data from T2DM donors with Ab or the autoimmune diabetes associated DR3/DR4 allelic class II combination showed reduction in beta cell mass as well as presence of autoimmune-associated pattern A pathology in subjects with either islet autoantibodies or the DR3/DR4 genotype. In conclusion, we provide compelling evidence indicating that islet Ab positive long-term T2DM patients exhibit profound impairment of insulin secretion as well as reduced beta cell mass seemingly determined by an immune-mediated injury of pancreatic β-cells. Deciphering the mechanisms underlying beta cell destruction in this subset of diabetic patients may lead to the development of novel immunologic therapies aimed at halting the disease progression in its early stage.

Impaired vibrotactile sense at low frequencies in fingers in autoantibody positive and negative diabetes

Vibration thresholds in index and little finger pulps in subjects with autoantibody [GADA, IA-2A and/or ICA] positive and negative diabetes 20 years after diagnosis were higher than in age-matched controls at low frequencies (8 and 16 Hz), irrespective of HbA1c values, indicating selective impairment of Meissner's corpuscles and/or their innervating axons.

Clinical evolution of beta cell function in youth with diabetes: the SEARCH for Diabetes in Youth study

AIMS/HYPOTHESIS

Few studies have explored the epidemiology of beta cell loss in youth with diabetes. This report describes the evolution and major determinants of beta cell function, assessed by fasting C-peptide (FCP), in the SEARCH for Diabetes in Youth study.

METHODS

Participants were 1,277 youth with diabetes (948 positive for diabetes autoantibodies [DAs] and 329 negative for DAs), diagnosed when aged <20 years, who were followed from a median of 8 months post diagnosis, for approximately 30 months. We modelled the relationship between rate of change in log FCP and determinants of interest using repeated measures general linear models.

RESULTS

Among DA-positive youth, there was a progressive decline in beta cell function of 4% per month, independent of demographics (age, sex, race/ethnicity), genetic susceptibility to autoimmunity (HLA risk), HbA(1c) and BMI z score, or presence of insulin resistance. Among DA-negative youth, there was marked heterogeneity in beta cell loss, reflecting an aetiologically mixed group. This group likely includes youths with undetected autoimmunity (whose decline is similar to that of DA-positive youth) and youth with non-autoimmune, insulin-resistant diabetes, with limited decline (~0.7% per month).

CONCLUSIONS/INTERPRETATION

SEARCH provides unique estimates of beta cell function decline in a large sample of youth with diabetes, indicating that autoimmunity is the major contributor. These data contribute to a better understanding of clinical evolution of beta cell function in youth with diabetes, provide strong support for the aetiological classification of diabetes type and may inform tertiary prevention efforts targeted at high-risk groups.

Characteristics and Prevalence of Latent Autoimmune Diabetes in Adults (LADA)

Diabetes, one of the most commonly seen metabolic disorders, is affecting a major area of population in many developing as well as most of the developed countries and is becoming an alarming concern for the rising cost of the healthcare system. Latent Autoimmune Diabetes in Adults (LADA) is a form of diabetes which is less recognized and underdiagnosed type of diabetes which appears to have characteristics of both type 1 (autoimmune in nature) and type 2 diabetes (adult age at onset and initial response to oral hypoglycemic agents). An epidemiological study was carried out on 500 patients in the western region of India. Various parameters such as age at onset, duration of diabetes, gender, basal metabolic index (BMI), type of diabetes, family history, HbA1c levels, cholesterol levels, and current treatment regimen were evaluated and correlated with type 1 and type 2 diabetes. Moreover, diagnostic markers for LADA, namely, GAD autoantibodies and C-peptide levels, were determined for 80 patients selected from the epidemiological study. Some of the results obtained were found to be consistent with the literature whereas some results were found to be contradictory to the existing data.

No signs of progressive beta cell damage during 20 years of prospective follow-up of autoantibody-negative diabetes

Both type 1 and type 2 diabetes are considered to be associated with different degrees of progressive beta cell damage. However, few long-term studies have been made. Our aim was to study the clinical course of 20 years of diabetes disease, including diabetes progression, comorbidity, and mortality in a prospectively studied cohort of consecutively diagnosed diabetic patients. Among all 233 patients diagnosed with diabetes during 1985-1987 in Malmö, Sweden, 50 of 118 surviving patients were followed-up after 20 years. The age at diagnose was 42.3 ± 23.1 and 57.5 ± 13.6 years for antibody-positive and antibody-negative patients, respectively. HbA1c and plasma lipids were analyzed with regard to metabolic control. Islet antibody-negative patients at diagnosis had highly preserved C-peptide levels after 20 years in contrast to antibody-positive patients (antibody negative: C-peptide 0 years 0.78 ± 0.47 and 20 years 0.70 ± 0.46 (nmol/l), P = 0.51 and antibody positive: C-peptide 0 years 0.33 ± 0.35 and 20 years 0.10 ± 0.18; P < 0.001. Islet antibodies but not age, BMI, or C-peptide at diagnosis were predictors of C-peptide levels at 20 years when analyzed by logistic regression (P < 0.05). HbA1c did not differ between the groups after 20 years. The 20-year mortality was higher among antibody-negative patients, dependent on the higher age at diagnosis in this group (number of deaths: antibody positive: 18 of 56 vs. antibody negative: 109 of 188, P < 0.001). Of the deceased, 79% had died from diseases or complications that may be associated with diabetes. We found no progressive beta cell damage in autoantibody-negative diabetes at a 20-year follow-up of the clinical course of diabetes.

Incidence of type 1 and type 2 diabetes in adults and children in Kronoberg, Sweden

All newly diagnosed diabetes in Kronoberg during 3 years was registered, with blood samples from 1630/1666 (97.8%) adults. Those positive for GADab and/or ICA and/or C-peptide<0.25nmol/L (0.7%) were classified as type 1 diabetes, the remaining as type 2. Incidence of type 1 in 0-19-year-olds was 37.8(36.1-39.6, 95%CI) and in 20-100 year-olds 27.1(25.6-27.4) per 100 000 and year, it was bimodal with equal peaks in 0-9 year-olds and in 50-80-year-olds. Adults had type 2 incidence 378 (375-380), children 3.1 (2.6-3.6). Among adults 6.9% had type 1 and 93.1% type 2. Among antibodypositive adults (n=101), GADab were present in 90%, ICA in 71%, both GADab and ICA in 61%. Ophthalmology contact as second source was confirmed for 98%. There were no gender differences in type 1 in any age group, small ones in pediatric subgroups. In type 2 men predominated in ages above 40 years. Incidences of type 1 diabetes in both children and adults were very high and as high above age 50 years as in children. Incidence of type 2 was the highest reported from Sweden, to which new diagnostic criteria, a high degree of case-finding, and many elders, may have contributed, but results may also reflect a true increase in incidence of both types of diabetes.

Latent autoimmune diabetes in adults (LADA): usefulness of anti-GAD antibody titers and benefit of early insulinization

OBJECTIVE

To determine the clinical and laboratory parameters and the progression to insulin requirement in two groups of LADA patients separated according to GADA titers, and to evaluate the benefit of early insulinization in patients at high risk of premature beta-cell failure (high GADA titers).

METHODS

Among the diabetic adults seen at our service and screened for GADA at diagnosis, 54 were diagnosed with LADA and classified as having low (> 1 U/ml and < 17.2 U/ml) or high (> 17.2 U/ml) GADA titers. Fifty-four patients with type 2 diabetes (GADA-) were selected for comparison. In addition, 24 patients who had GADA titers > 20 U/ml and who were not initially insulinized were compared to 16 patients who were insulinized at diagnosis.

RESULTS

Insulin resistance was higher in the GADA- group, followed by patients with low GADA titers. BMI and the frequency of arterial hypertension, elevated triglycerides and reduced HDL cholesterol were lower in the high GADA+ group, with no difference between the GADA- or low GADA+ groups. The high GADA+ group showed a greater reduction and lower levels of C-peptide and required insulin earlier during follow-up. Patients with GADA titers > 20 U/ml and insulinized early presented no significant variation in C-peptide levels, had better glycemic control and required a lower insulin dose than patients who were insulinized later.

CONCLUSION

We agree that patients with LADA should be differentiated on the basis of GADA titers and that patients with GADA titers > 20 U/ml benefit from early insulinization.

The rise and fall of insulin secretion in type 1 diabetes mellitus

An understanding of the natural history of beta cell responses is an essential prerequisite for interventional studies designed to prevent or treat type 1 diabetes. Here we review published data on changes in insulin responses in humans with type 1 diabetes. We also describe a new analysis of C-peptide responses in subjects who are at risk of type 1 diabetes and enrolled in the Diabetes Prevention Trial-1 (DPT-1). C-peptide responses to a mixed meal increase during childhood and through adolescence, but show no significant change during adult life; responses are lower in adults who progress to diabetes than in those who do not. The age-related increase in C-peptide responses may account for the higher levels of C-peptide observed in adults with newly diagnosed type 1 diabetes compared with those in children and adolescents. Based on these findings, we propose a revised model of the natural history of the disease, in which an age-related increase in functional beta cell responses before the onset of autoimmune beta cell damage is an important determinant of the clinical features of the disease.

Latent autoimmune diabetes in adults: definition, prevalence, beta-cell function, and treatment

Latent autoimmune diabetes in adults (LADA) is a disorder in which, despite the presence of islet antibodies at diagnosis of diabetes, the progression of autoimmune beta-cell failure is slow. LADA patients are therefore not insulin requiring, at least during the first 6 months after diagnosis of diabetes. Among patients with phenotypic type 2 diabetes, LADA occurs in 10% of individuals older than 35 years and in 25% below that age. Prospective studies of beta-cell function show that LADA patients with multiple islet antibodies develop beta-cell failure within 5 years, whereas those with only GAD antibodies (GADAs) or only islet cell antibodies (ICAs) mostly develop beta-cell failure after 5 years. Even though it may take up to 12 years until beta-cell failure occurs in some patients, impairments in the beta-cell response to intravenous glucose and glucagon can be detected at diagnosis of diabetes. Consequently, LADA is not a latent disease; therefore, autoimmune diabetes in adults with slowly progressive beta-cell failure might be a more adequate concept. In agreement with proved impaired beta-cell function at diagnosis of diabetes, insulin is the treatment of choice.

Natural history of beta-cell function in type 1 diabetes

Despite extensive and ongoing investigations of the immune mechanisms of autoimmune diabetes in humans and animal models, there is much less information about the natural history of insulin secretion before and after the clinical presentation of type 1 diabetes and the factors that may affect its course. Studies of insulin production previously published and from the Diabetes Prevention Trial (DPT)-1 suggest that there is progressive impairment in insulin secretory responses but the reserve in response to physiological stimuli may be significant at the time of diagnosis, although maximal responses are more significantly impaired. Other factors, including insulin resistance, may play a role in the timing of clinical presentation along this continuum. The factors that predict the occurrence and rapidity of decline in beta-cell function are still largely unknown, but most studies have identified islet cell autoantibodies as predictors of future decline and age as a determinant of residual insulin production at diagnosis. Historical as well as recent clinical experience has emphasized the importance of residual insulin production for glycemic control and prevention of end-organ complications. Understanding the modifiers and predictors of beta-cell function would allow targeting immunological approaches to those individuals most likely to benefit from therapy.

Beta cell function and response to treatment in Nigerians with Type 2 diabetes mellitus

There are scant data from African populations on the association between beta-cell function and response to treatment with oral hypoglycaemic agents in Type 2 diabetes mellitus (T2DM). Fasting plasma C-peptide (FCP) and glucagon-stimulated C-peptide (GSCP) levels were measured in 116 Nigerians with T2DM at a university teaching hospital. After 9 months of follow-up and treatment, they were categorized into three groups based on response to treatment: (A) good control but not on maximum sulphonylurea (SU) therapy, (B) inadequate control but not on maximum SU therapy and (C) on maximum SU therapy+/-insulin or biguanide. Logistic regression models were used to investigate how well C-peptide levels predicted the subjects belonging to Group C who are likely to require insulin. The mean FCP and mean GSCP levels of Group C were significantly lower than in the other groups (p=0.024; p= <0.001 respectively). A GSCP cut-off value of < or =1.3 ng/mL predicted membership of Group C with 85% sensitivity and 89% specificity while a cut-off of < or =1.8 ng/mL was associated with 91% sensitivity and 66% specificity. In resource-poor settings where inadequate treatment are common, estimation of GSCP may be useful in predicting treatment response and should be weighed against the cost of inadequate therapy with higher morbidity and mortality.

Early parasympathetic neuropathy associated with elevated fasting plasma C-peptide concentrations and late parasympathetic neuropathy with hyperglycaemia and other microvascular complications

AIMS

To examine the relationship between parasympathetic neuropathy, hyperinsulinaemia, glycaemic control (HbA(1c)), and future diabetic complications.

METHODS

We assessed parasympathetic nerve function [expiration/inspiration (E/I) ratio], glomerular filtration rate (GFR), glycaemic control (HbA(1c)), fasting plasma (f-p-) C-peptide in 82 Type 2 diabetic patients (age 61 +/- 1 years) 5 and 12-15 years after diagnosis. Diabetic retinopathy was assessed 15 years after diagnosis.

RESULTS

High HbA(1c) values in the first study were associated with retinopathy (with 8.6 +/- 2.0 vs. without retinopathy 6.2 +/- 1.9%; P < 0.0001) and disturbed parasympathetic nerve function (low E/I ratio; r(s) = -0.41; P = 0.0061) in the second study, as well as with deteriorations in GFR between the first and second study (r(s) = 0.62; P < 0.0001). Patients with parasympathetic neuropathy in the first study had significantly higher f-p-C-peptide concentrations than those without 3 years (1.20 +/- 0.43 vs. 0.86 +/- 0.40 nmol/l; P = 0.0015) and 5 years (1.20 +/- 0.44 vs. 0.82 +/- 0.33 nmol/l; P < 0.0001), but not 15 years after diagnosis.

CONCLUSION

High HbA(1c) values 5 years after diagnosis of Type 2 diabetes were associated with retinopathy, disturbed parasympathetic nerve function, and deterioration in GFR 7-10 years later. Parasympathetic neuropathy 5 years after diagnosis was associated with high C-peptide concentrations. Parasympathetic nerve function has to be considered when beta-cell function is evaluated. Hyperglycaemia is an important factor for the development of complications in Type 2 diabetes.

Immune-mediated disease and secondary failure to oral therapy in type 2 diabetes mellitus

PURPOSE

To determine the proportion of adults with type 2 diabetes, who developed secondary failure to oral medications that had immune-mediated diabetes (IMD).

SUBJECTS AND METHODS

One hundred and eight subjects who failed to oral therapy were screened for autoantibodies (ICA, IAA, IA-2A, and GADA(65)) and HLA DR/DQ markers of IMD.

RESULTS

Mean age was 49 years and mean body mass index (BMI) was 31.5 kg/m(2); 21.3% were non-Hispanic White (NHW), 32.3% Latin American (LA), and 43.2% African American (AA). Fourteen percent had one or more autoantibodies [Ab(+)]: five NHW, three LA, and seven AA. Ab(+) patients were younger (P=.03) and had lower body weight (P=.05) than Ab(-) patients. HLA markers of susceptibility for IMD were identified in 64% Ab(+) and in 43% Ab(-) (chi(2), P=.46).

CONCLUSIONS

These results suggest that secondary failure to oral therapy can be due to continuing IMD in obese, type 2 diabetic individuals of varying ethnic backgrounds than those who have been traditionally associated with autoimmune type 1 diabetes. Screening for markers for IMD at diagnosis could be a useful way to predict those likely to develop secondary failure to oral therapy and may assist in the selection of medical therapy.

Similar genetic features and different islet cell autoantibody pattern of latent autoimmune diabetes in adults (LADA) compared with adult-onset type 1 diabetes with rapid progression

OBJECTIVE

To compare the clinical parameters, C-peptide levels, pattern of islet cell-specific autoantibodies, and prevalence of predisposing genotypes in subjects with latent autoimmune diabetes in adults (LADA) and those with adult-onset type 1 diabetes with rapid progression.

RESEARCH DESIGN AND METHODS

We evaluated the clinical parameters, C-peptide levels, and islet cell-specific autoantibodies in 54 LADA, 57 adult-onset type 1 diabetic, and 190 type 2 diabetic patients. Islet cell autoantibodies were also compared between subgroups of newly diagnosed patients with LADA and those with newly diagnosed adult-onset and childhood-onset type 1 diabetes. The genetic study was performed in subjects with LADA and those with adult-onset type 1 diabetes in comparison with a control population.

RESULTS

There were no differences in the clinical parameters between LADA and adult-onset type 1 diabetes. Patients with LADA had lower BMI (P < 0.0001), waist-to-hip ratio (0.0029), total cholesterol (P = 0.001), and triglycerides (P = 0.001); higher HDL cholesterol levels (P < 0.0001); and lower prevalence of hypertension (P = 0.0028) compared with patients with type 2 diabetes. C-peptide levels were similar at onset (P = 0.403) but decreased less rapidly in LADA than in adult-onset type 1 diabetes (P = 0.0253). Single-autoantibody positivity was more often seen in LADA than in type 1 diabetes (P = 0.0001). The prevalence of predisposing HLA-DQB1*0302, -DR4, -DR3, and -DR3/DR4 genotypes and the DR4-DQB1*0302 haplotype were increased in both LADA and adult-onset type 1 diabetic subjects compared with the control population. There were no differences in the frequencies of these risk alleles and haplotypes between the two patient groups.

CONCLUSIONS

Subjects with LADA had clinical characteristics similar to those with adult-onset type 1 diabetes with rapid progression. C-peptide levels did not differ at onset but decreased less rapidly in LADA. Patients with LADA rather had single islet cell-specific autoantibody positivity. The prevalence of HLA-DQB1*0302, -DR4, -DR3, and -DR3/DR4 risk alleles and the DR4-DQB1*0302 high-risk haplotype did not differ in the two forms of autoimmune diabetes.

A 12-year prospective study of the relationship between islet antibodies and beta-cell function at and after the diagnosis in patients with adult-onset diabetes

To clarify the relationships between islet antibodies (islet cell antibody [ICA], GAD antibody [GADA], and IA-2 antibody [IA-2A]) versus the progression of beta-cell dysfunction, we have followed a group of diabetic patients from their diagnosis at 21-73 years of age. Patients with ICA had high levels of GADA and/or IA-2A at diagnosis and a more severe beta-cell dysfunction 5 years after diagnosis than those with only GADA in low concentrations. The aim of the current 12-year follow-up study was to examine the further progression of beta-cell dysfunction in relation to islet antibodies at and after diagnosis. Among 107 patients, complete beta-cell failure 12 years after diagnosis was restricted to those with islet antibodies at diagnosis (16 of 21 [77%] with multiple antibodies and 4 of 5 [80%] with only GADA). In contrast, among antibody-negative patients, fasting P-C-peptide levels were unchanged. Most GADA-positive patients (22 of 27 [81%]) remained GADA positive after 12 years. Associated with decreasing fasting P-C-peptide levels (0.85 nmol/l [0.84] at diagnosis vs. 0.51 nmol/l [0.21] 12 years after diagnosis, P < 0.05), ICA developed after diagnosis in 6 of 105 originally antibody negative mostly overweight patients. In conclusion, multiple islet antibodies or GADA alone at diagnosis of diabetes predict future complete beta-cell failure. After diagnosis, GADA persisted in most patients, whereas ICA development in patients who were antibody negative at diagnosis indicated decreasing beta-cell function.

Beta cell rest and recovery--does it bring patients with latent autoimmune diabetes in adults to euglycemia?

Diabetes mellitus in humans is a heterogeneous disorder classified clinically into two main types. The diagnosis of type 1 versus type 2 diabetes is made phenotypically using criteria such as age at onset, abruptness of hyperglycemic symptoms, presence of ketosis, degree of obesity and the perceived need for insulin replacement. The pathogeneses of type 1 and type 2 diabetes are believed to be different. Type 1 diabetes is an autoimmune disease mediated by cellular effector mechanisms; whereas classic type 2 diabetes is not autoimmune but results from insulin resistance and a nonautoimmune insulin secretory defect. Most type 1 diabetes patients are diagnosed in childhood or young adulthood before the age of 35 years. However, there is clearly a subgroup of patients clinically diagnosed with type 2 diabetes who are greater than 35 years of age and have evidence of autoimmunity. The disease of these autoantibody-positive type 2 diabetics is often termed latent autoimmune diabetes in adults (LADA), slowly progressive type 1 diabetes, latent type 1 diabetes, and type 1.5 diabetes. This group of patients comprises approximately 10-15% of Caucasian type 2 diabetes patients. Type 1.5 diabetes patients tend to present with islet cell autoantibodies, islet-reactive T cells, higher HbA(1c) levels, lower C peptide, and a propensity toward insulin dependency compared to autoantibody-negative classic type 2 diabetes subjects.

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.

Autonomic neuropathy in Type 2 diabetic patients is associated with hyperinsulinaemia and hypertriglyceridaemia

AIMS

To clarify whether parasympathetic neuropathy in Type 2 diabetic patients is associated with features of the insulin resistance syndrome.

METHODS

Blood pressures, glycaemic control (HbA1c), plasma lipids, residual beta-cell function (fasting plasma C-peptide), autonomic nerve function, urinary albumin excretion and glomerular filtration rate (Cr-EDTA clearance) were evaluated in 82 Type 2 diabetic patients (age 63+/-years) 5 years after diagnosis of diabetes.

RESULTS

Parasympathetic neuropathy (an abnormal age corrected E/I ratio) was found in 24/82 (29%) patients. After adjustment for body mass index (BMI), patients with parasympathetic neuropathy had elevated fasting plasma C-peptide (P < 0.001) and triglyceride (Tg) (P < 0.05) levels compared with patients without parasympathetic neuropathy. In addition, the age corrected E/I ratio correlated inversely with Tg (r=-0.31; P<0.01) and fasting plasma C-peptide (r=-0.32; P < 0.01) in the Type 2 diabetic patients.

CONCLUSION

Autonomic neuropathy 5 years after diagnosis of Type 2 diabetes is associated with an unfavourable metabolic risk profile.

The frequency and severity of retinopathy are related to HbA1c values after, but not at, the diagnosis of NIDDM

OBJECTIVES

To examine the relationship between previous glycaemic exposure and prevalence of retinopathy 8 years after diagnosis of diabetes in 58 islet cell antibodies (ICA)-negative noninsulin-dependent diabetes mellitus (NIDDM) patients and in a group of 14 ICA-positive 'NIDDM' and insulin-dependent diabetes mellitus (IDDM) patients.

DESIGN AND METHODS

The Wisconsin retinopathy scale was used to assess the retinopathy which was graded into mild, moderate and severe nonproliferative diabetic retinopathy (NPDR), or proliferative retinopathy (PDR). The frequency and severity of retinopathy was related to HbA1c levels at diagnosis, and 3 and 5 years later.

RESULTS

Thirty of the 58 ICA-negative NIDDM patients (52%) but only 2 of the 14 ICA-positive 'NIDDM' or IDDM patients (14%) had mild-moderate-severe NPDR 8 years after diagnosis (P = 0.02). None had PDR. Retinopathy 8 years after diagnosis in NIDDM (= 58 ICA-negative patients) was correlated with the degree of glycaemic control (HbA1c levels) at 3 and 5 years after diagnosis, but not to HbA1c levels at diagnosis. The relative risk for a higher average HbA1c (per percentage) at 3 and 5 years was 1.56 for any retinopathy vs. no retinopathy (95% confidence interval 1.1-2.2; P = 0.01) and 1.68 for moderate to severe NPDR in comparison with no DR and mild NPDR (95% confidence interval 1.0-2.8; P = 0.04).

CONCLUSIONS

Retinopathy after 8 years of diabetes in NIDDM patients was associated with impaired glycaemic control during previous years but not with glycaemic control at baseline. Good glycaemic control may prevent retinopathy in patients with NIDDM.

Measurement of antibodies against glutamic acid decarboxylase 65 (GADA): two new 125I assays compared with [35S]GAD 65-ligand binding assay

Recently, 65-kDa glutamic acid decarboxylase (GAD 65) antibodies (GADA) have been introduced as autoimmune markers in blood to confirm the diagnosis of insulin-dependent diabetes mellitus (IDDM). In this study, to evaluate two new assays that use 125I-labeled GAD 65, we assayed samples from 100 children with recent onset of diabetes and 100 control children; the results were compared with those of a [35S]GADA assay and with results for islet cell antibodies (ICA), the conventional autoimmune marker. Receiver operating characteristic (ROC) curve analysis showed one of the new assays (from RSR) to be more sensitive (P = 0.01) than the comparison ([35S]GADA) assay, whereas the second new assay (from Elias) was less sensitive (P &lt;0.001). The GADA frequency at 97.5% specificity was greatest in the comparison assay: 63 of 100 vs 41 of 100 (P &lt; 0.01) and 53 of 100 (P = 0.16) in the RSR and Elias assays, respectively. Almost all GADA-positive patients had ICA, but one-third of the ICA-positive patients was GADA-negative. Accordingly, adding GADA analysis results to ICA testing increased the frequency of detection of autoimmune markers only slightly (from 81% to 85%). In conclusion, at 97.5% specificity the [35S]GADA assay seemed to be more efficient than the 125I assays, although the difference was significant only for the Elias 125I assay. Antigen-specific antibodies other than GADA may explain the difference in GADA and ICA frequencies.