The HLA system and insulin dependent diabetes: recent findings and prospects for disease prediction

Our knowledge of the genetics of insulin dependent diabetes (IDDM), and in particular the HLA system, has gained considerable expansion thanks to the application of molecular biology. The genetic susceptibility to the disease is linked to the HLA region, particularly at DQ-alpha and DQ-beta chain genes. Particular amino acid other than aspartic acid in position 57 of the DQ beta chain and the presence of an arginine in position 52 of the DQ alpha chain and to how these markers can be used to identify subjects at risk for developing IDDM. The identification of such subjects may be useful for the development of strategies aimed to prevent the disease and in addition may offer a new insight into population screening.

In situ islet T cell receptor variable region gene usage in the nonobese diabetic mouse

Several features of the genetics and immunopathology of diabetes in the nonobese diabetic (NOD) mouse, which spontaneously develops type I diabetes, are shared with the human disease. Immunohistochemical studies support the concept that T lymphocytes are the major components of inflammatory cells in the pancreatic islets and these cells may play a critical role in the destruction of the beta cells leading to diabetes. Therefore, we examined whether particular TCR-beta variable region genes were utilized by in situ islet T cells at different stages (4 - 5, 7, 14 - 15 and 16 weeks of age) of the disease process. Dot-blot hybridization was performed using RNA prepared from isolated islets, thymus, spleen, peripheral blood leukocytes and axillary lymph nodes of 10 to 15 mice pooled for each data point. Ten different TCR V-beta probes were used for the analyses. Limited usage of islet V-beta genes was observed only at the early prediabetic stage (4 - 5 weeks old) of the disease. At later stages of the disease (7 - 16 weeks old), no preferential usage of TCR genes was observed in the islets compared to those of peripheral lymphoid organs. These data suggest that only certain types of T cells bearing particular TCR V-beta genes may be responsible for initiating and perpetuating infiltration of immune cells into the islets and these particular T cells are only identified at the very early stages of the autoimmune process.

Islet amyloid polypeptide plasma concentrations in individuals at increased risk of developing type 2 (non-insulin-dependent) diabetes mellitus

To study whether abnormal secretion of islet amyloid polypeptide is involved in the development of insulin resistance and impaired insulin secretion in Type 2 (non-insulin-dependent) diabetes mellitus, we measured islet amyloid polypeptide concentrations in 56 first-degree relatives of Type 2 diabetic subjects and in 10 healthy control subjects. Fasting islet amyloid polypeptide concentrations were similar in control subjects, glucose-tolerant and glucose-intolerant relatives (8 +/- 1, 9 +/- 1 and 11 +/- 2 fmol/ml; p = NS). The area under the islet amyloid polypeptide curve measured during an oral glucose load was larger in glucose-intolerant relatives (115 +/- 13 fmol/ml) compared to glucose tolerant relatives and control subjects (88 +/- 3 and 79 +/- 12 fmol/ml; p less than 0.05). The insulin response during the oral glucose load was inversely correlated with the rate of glucose disposal measured during a euglycaemic hyperinsulinaemic clamp (r = -0.725; p less than 0.01), while no significant correlation was observed between the corresponding values for islet amyloid polypeptide and glucose disposal (r = -0.380; p = NS). Hypersecretion of islet amyloid polypeptide is observed in glucose-intolerant first-degree relatives of patients with Type 2 diabetes. Since these patients are characterized by insulin resistance and abnormal first-phase insulin secretion, the putative role of islet amyloid polypeptide in the development of these abnormalities remains to be established. It is however, unlikely that islet amyloid polypeptide is involved in the development of insulin resistance as insulin-resistant relatives with normal glucose-tolerance showed normal islet amyloid polypeptide concentrations.

Prognostically significant heterogeneity of cytoplasmic islet cell antibodies in relatives of patients with type I diabetes

A significant proportion of relatives of patients with insulin-dependent (type I) diabetes with high titers of cytoplasmic islet cell autoantibodies (ICAs) do not progress to overt diabetes with up to 8 yr of follow-up. This may reflect that follow-up of such relatives has not been long enough to observe diabetes, that despite expression of identical ICAs, some relatives will not progress to diabetes; or that there is heterogeneity in what is identified as ICA. We identified a subset of ICA that was restricted in its species (not reacting with mouse islets) and cell-type reactivity within islets (beta-cell specific). Only one of eight relatives whose sera had the restricted pattern of reactivity progressed to overt diabetes, and on sequential evaluation, all but the one relative who progressed to diabetes have maintained normal first-phase insulin secretion to intravenous glucose. In contrast, by life-table analysis, 70% of relatives expressing nonrestricted ICA became diabetic within 5 yr of follow-up (1 of 8 vs. 16 of 25 diabetic at last follow-up, P less than 0.02). Moreover, preliminary data suggest a significant association of the human leukocyte antigen DQB1*0602 allele of DR2 haplotypes with the restricted ICA pattern (4 of 5 DQB1*0602 restricted vs. 0 nonrestricted ICA, P = 0.006). We propose that expression of a genetically determined restricted ICA pattern confers a markedly lower risk for progression to diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)

Metformin normalizes nonoxidative glucose metabolism in insulin-resistant normoglycemic first-degree relatives of patients with NIDDM

Many first-degree relatives of patients with non-insulin-dependent diabetes mellitus (NIDDM) are characterized by insulin resistance. Because metformin improves peripheral insulin sensitivity, we examined the acute effect of metformin and placebo on glucose and lipid metabolism in nine insulin-resistant first-degree relatives of NIDDM patients with the euglycemic insulin-clamp technique combined with indirect calorimetry and infusion of [3-3H]glucose. Either placebo or 500 mg metformin was taken in random order twice the day before and once 1 h before the clamp. Nine healthy individuals without family history of diabetes served as control subjects. Basal plasma glucose was normal and did not differ between the metformin and the placebo study (4.8 +/- 0.2 vs. 5.0 +/- 0.2 mM) and neither did basal hepatic glucose production (10.59 +/- 0.54 vs. 10.21 +/- 0.80 mumol.kg-1.min-1). Insulin-stimulated glucose disposal was significantly increased by 25% after metformin compared with placebo (26.67 +/- 2.87 vs. 21.31 +/- 1.73 mumol.kg-1.min-1, P less than 0.05). The enhancement in glucose utilization was primarily due to normalization of nonoxidative glucose disposal (from 8.02 +/- 1.35 to 15.07 +/- 2.69 mumol.kg-1.min-1, P less than 0.01, vs. 15.65 +/- 2.72 mumol.kg-1.min-1 in control subjects). In contrast, glucose oxidation during the clamp was slightly lower after metformin compared with both placebo (11.59 +/- 0.83 vs. 13.30 +/- 1.00 mumol.kg-1.min-1, P = 0.06) and healthy control subjects (15.68 +/- 1.38 mumol.kg-1.min-1, P less than 0.05). We conclude that acutely administered metformin improves peripheral insulin sensitivity in insulin-resistant normoglycemic individuals primarily by stimulating the nonoxidative pathway of glucose metabolism.

Linkage of faulty major histocompatibility complex class I to autoimmune diabetes

Pancreatic islet cells are the targets of an autoimmune response in type I diabetes. In the nonobese diabetic (NOD) mouse model of autoimmune diabetes, expression of major histocompatibility complex (MHC) class I proteins was inversely correlated with diabetes; in this mouse a mutation in the MHC class II-linked gene for the putative MHC class I peptide transporter was also present. Mice deficient in MHC class I expression because they do not produce beta 2-microglobulin also developed late onset autoimmune diabetes. In cells from humans with type I diabetes expression of MHC class I was decreased; subsets of prediabetics categorized as most likely to become hyperglycemic also had low MHC class I. T cell responses to self antigens are faulty in diabetics. In sets of genetically identical twins that are discordant for diabetes, the defect appeared to reside with the antigen presenting cell. Thus, a lack of surface MHC class I protein is associated with autoimmune diabetes; the concomitant defect in antigen presentation may impair the development of self tolerance, which could result in autoimmune disease.

Metabolic state of the pancreas affects end-point titre in the islet cell antibody assay

Quantification of islet cell antibodies is used increasingly to evaluate pre-clinical Type 1 (insulin-dependent) diabetes mellitus. If expression of the antigen(s) reacting with islet cell antibodies varies depending upon the functional state of the pancreatic islets, this may partly explain differences in assay sensitivity between laboratories. To address this question we altered Beta-cell function in Osborn-Mendel rats, by dietary manipulation prior to killing. Rats were fed chow (n = 7) or a high sucrose/high fat "cafeteria" diet (n = 8) or were fasted for 18 h (n = 6) until immediately prior to killing. Using frozen sections of these rat pancreata in the indirect immunofluorescent test for islet cell antibodies, we determined the end-point titre for 18 sera in which islet cell antibodies had been previously quantified in our standard human pancreas assay. These sera included ten positive sera and eight normal negative control sera. The four most strongly positive sera gave significantly higher end-point titres on "cafeteria" diet-fed pancreata and lower titres on fasted pancreata (p less than 0.04 to 0.002). None of non-diabetic control sera were positive on any substrate. These data suggest that islet antigen expression is increased when Beta-cell function is increased by dietary manipulation. Improved sensitivity in the islet cell antibody assay might be possible by altering Beta-cell function before or immediately after pancreas collection.

T-lymphocyte changes linked to autoantibodies. Association of insulin autoantibodies with CD4+CD45R+ lymphocyte subpopulation in prediabetic subjects

The onset of insulin-dependent (type I) diabetes is predictable before hyperglycemia by the presence of islet cell autoantibodies (ICAs) and competitive insulin autoantibodies (CIAAs). CIAA+ICA+ first-degree relatives of individuals with type I diabetes have increased numbers of CD4 cells bearing the CD45R antigen and reciprocal depressions of the CD4 cells bearing the CD29 determinant. In addition, depressed CD4/CD8 ratios are present. In this study, we investigated the correlation between autoantibody levels and T-lymphocyte changes in the prediabetic state. The data demonstrate a clear linear relationship between rising CIAA levels, a marker of disease rate, and rising elevations in the CD4+CD45R+/CD4+CD29+ ratio in 37 CIAA+ICA+ and CIAA+ICA- relatives (r = 0.93). In marked contrast, the degree of CD4/CD8 depression found in individuals with prediabetes or long-term diabetes failed to correlate with either CIAA (r = 0.32) or ICA (r = 0.29) levels. The investigation of T-lymphocyte changes in siblings of individuals with type I diabetes with different stable autoantibody patterns (CIAAs and/or ICAs), and thus varying risks for diabetes, revealed differences in the prediabetic groups. Fifteen CIAA+ICA- relatives with high CIAA levels (greater than 80 nU/ml) had high CD4+CD45R+/CD4+CD29+ ratios (P = 0.03) and depressed CD4/CD8 ratios (P = 0.008). In contrast, CIAA+ICA- relatives with low CIAA levels (39-80 nU/ml), and thus low risk of diabetes, had no alteration in their CD4/CD8 ratio (P = 0.75) or CD4+CD45R+/CD4+CD29+ ratio (P = 0.33). Nineteen CIAA-ICA+ siblings with a predicted intermediate risk for diabetes showed heterogeneity in the presence of T-lymphocyte abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)

Predictive value of intravenous glucose tolerance test insulin secretion less than or greater than the first percentile in islet cell antibody positive relatives of type 1 (insulin-dependent) diabetic patients

We have followed-up 35 islet cell antibody-positive first degree relatives of patients with Type 1 (insulin-dependent) diabetes mellitus for an average of 1,300 days with sequential intravenous glucose tolerance tests. At the time of analysis and manuscript submission approximately half (18 of 35) had developed diabetes during follow-up. At initial intravenous glucose tolerance test, 11 had a 1 + 3 min insulin secretion below the first percentile of insulin secretion compared to 225 similarly studied normal control subjects. Six islet cell antibody positive relatives on follow-up developed an intravenous glucose tolerance test less than the first percentile. Fifteen out of 17 (88%) of these islet cell antibody positive relatives with secretion ever found to be below the first percentile are now overtly diabetic (positive predictive value = 88%) and insulin-treated, while only 3 of 18 (17%) without an intravenous glucose tolerance test demonstrating loss of first phase insulin secretion have progressed to diabetes (with approximately 1,300 days of follow-up for both groups relative risk or odds ratio with intravenous glucose tolerance test ever below vs never below the first percentile = 38, p less than 0.001). Intravenous glucose tolerance test response below the first percentile preceded diabetes by an average of 656 days. Even when first phase insulin secretion is below the first percentile, the absolute value of 1 + 3 min insulin above basal insulin correlates with the time to development of diabetes (r = 0.586, p less than 0.001). With our current duration of follow-up, the negative predictive value (intravenous glucose tolerance test never below the first percentile) is 83%, and overall accuracy 86%. Incidence rates of diabetes development amongst our islet cell antibody positive relatives with follow-up while intravenous glucose tolerance test is below the first percentile is 0.48 per year (15 conversions to diabetes amongst 17 relatives in 30.8 patient years of follow-up) vs 0.05 per year (three diabetic patients in 55.5 patient years) with intravenous glucose tolerance test greater than the first percentile.

[Decrease of early insulin secretion, risk factor of insulin-dependent diabetes. Prospective study in families with diabetic children]

In order to study the capacity of the first phase insulin response (FPIR) for predicting insulin-dependent diabetes (IDDM), we have performed one or more intravenous glucose tolerance tests (IVGTT) and determined islet-cell antibodies (ICA) and HLA-types in 220 first degree relatives of IDDM patients (194 siblings, 26 offsprings) aged 2 to 29 years. They were prospectively followed for periods ranging from 18 months to 8 years. The immunological and metabolic changes in 9 subjects who have developed IDDM or impaired glucose tolerance during the study and in 3 ICA-positive non-diabetic subjects were compared to those in ICA-negative subjects. Although the mean FPIR (1 + 3 min. plasma insulin) was significantly lower in ICA-positive compared with ICA-negative subjects, a unique low FPIR had no predictive value at the individual level. At repeated tests, the two groups followed distinctive evolutive patterns: ICA-negative subjects usually had higher FPIRs at a 2nd test, while FPIRs remained low or still decreased in ICA-positive subjects. Follow-up of subjects at high risk showed good concordance between the different predictive factors: among the 9 subjects who have developed IDDM, 7 had persisting ICA, 8 were HLA-DR3, DR4; the FPIR was consistently low in 3 and low at least once in 4. Progressive loss of the FPIR allowing to predict the time of onset of IDDM, was not observed.

Prolonged exposure of pancreatic islets isolated from "pre-diabetic" non-obese diabetic mice to a high glucose concentration does not impair beta-cell function

In the early stages of Type 1 (insulin-dependent) diabetes mellitus patients present a deficient insulin response to glucose. The reasons for this defective response are unknown, but it has been suggested that it reflects a deleterious effect of excessive glucose stimulation on a reduced Beta-cell mass. Female non-obese diabetic (NOD) mice from our colony, at the age of 12-13 weeks, have a normal basal glycaemia but an impaired intravenous glucose tolerance test, insulitis and a defective insulin response to glucose. In order to characterize the potential effect of glucose on the Beta cells at that "pre-diabetic" stage, pancreatic islets were isolated from 12-13 week old female NOD mice. Immediately after isolation (day 0) the NOD islets displayed a defective insulin response to an acute stimulation with 16.7 mmol/l glucose. After seven days in culture at both 11 and 28 mmol/l glucose these islets showed an increased insulin release in response to an acute glucose stimulation. This increase was more pronounced in the islets cultured at 28 mmol/l glucose. Experiments performed in parallel, using islets obtained from a non-diabetes prone strain of mice (Naval Medical Research Institute, NMRI) showed that these islets had a similar insulin release in response to glucose both on day 0 and after seven days in culture at 11 mmol/l glucose. The insulin mRNA levels of NOD islets did not change over one week in culture at 11 or 28 mmol/l glucose, but culture at the high glucose concentration induced a decrease in the islet insulin content.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma proinsulin in first-degree relatives of type 2 diabetic subjects

Glucose intolerant relatives of Type 2 diabetic subjects have impaired insulin secretory responses to glucose but their proinsulin secretion has not been assessed. Plasma intact proinsulin was measured in 101 normoglycaemic and glucose intolerant first-degree relatives of Type 2 diabetic subjects both fasting and one hour after an infusion of glucose of 5 mg glucose.kg ideal weight.min-1. Geometric mean (+/- SD) plasma proinsulin increased from 2.4 (+2.5-1.2) and increased to 4.5 (+4.2-2.1) pmol/l at 1 hour (p less than 0.001). Linear regression revealed no relationship of fasting or achieved proinsulin with sex or obesity and a non-significant trend towards increasing fasting and achieved proinsulin with age and fasting plasma glucose. Proinsulin was assessed as a ratio to the simultaneous plasma C-peptide to estimate the relative amounts of insulin and proinsulin secreted by the beta-cells. Analysis of partial correlation coefficients, controlling for age and obesity, showed that the Achieved Proinsulin/Achieved C-peptide ratio was related to both fasting (r = 0.27, p = 0.004) and achieved plasma glucose (r = 0.25, p = 0.008). Glucose intolerant relatives (n = 37) had a small but significant increase in relative proinsulin secretion compared with normoglycaemic relatives (n = 64) (Achieved Proinsulin/Achieved C-peptide 0.07 +/- 0.05 vs 0.04 +/- 0.02 p less than 0.01). This is in accord with abnormal beta cell function being an early feature of Type 2 diabetes but does not distinguish between a primary beta-cell abnormality and a secondary effect of mild hyperglycaemia.

Antibodies to proinsulin and insulin as predictive markers of type 1 diabetes

The aim of the present study was to test whether proinsulin autoantibodies (IgG-PAA), insulin autoantibodies (IgG-IAA), and islet cell antibodies (ICA) may be used to identify subjects at risk for Type 1 diabetes. Pre-diabetic sera from 18 individuals who later developed diabetes were tested. Results were compared with 18 age-, sex-, and HLA-DR-matched non-diabetic control subjects from families with Type 1 diabetes. At a mean of 2.4 yr before the onset of diabetes, ICA were found in 13 patients (vs 0 control subjects, p less than 0.001), ELISA-determined IgG-IAA in 8 patients (vs 1 control subject, p less than 0.05) and ELISA-determined IgG-PAA in 4 patients (vs 2 control subjects, NS). ELISA-determined IgG-PAA do not appear to be useful predictors of the future development of Type 1 diabetes.

Development of carbohydrate intolerance in offspring of Asian Indian conjugal type 2 diabetic parents

Sixty-four offspring of conjugal diabetic parents (OCDP) who were normoglycaemic initially were available for a retest after a period of 4-9 years. Among them 10 (15.6%) had developed diabetes, 19 (29.7%) had developed IGT and the remaining 35 (54.7%) had maintained normal GTT. The predictive value of the baseline (initial) parameters was tested. Among the non-obese OCDP (BMI less than 25 and less than 27 for women and men, respectively), the initial sum of plasma glucose (sigma PG), and the mean increment of insulin during GTT (delta IRI), and the 2-h IRI values were higher in the group that developed abnormal glucose tolerance (P less than 0.05 compared to controls and normal OCDP). They also had higher insulin:glucose ratios, indicating higher insulin output for a given glucose concentration. On the other hand, among the obese OCDP the initial parameters did not differ between those who developed abnormal glucose tolerance and those who did not. Stepwise multiple regression analysis showed that the baseline sigma plasma glucose value was significantly related to the final 2-h plasma glucose when all the OCDP were taken together (P = 0.0023) and also in the non-obese OCDP (P = 0.0002). The other parameter which showed a relation to the final 2-h plasma glucose was the baseline delta IRI, although it was not statistically significant (P = 0.08). No such relation was observed in the obese group.

Analysis of metabolic progression to type I diabetes in ICA+ relatives of patients with type I diabetes

We intensively studied 5 islet cell-antibody-positive (ICA+) first-degree relatives of type I (insulin-dependent) diabetic patients before overt diabetes. In total, 55 intravenous glucose tolerance tests (IVGTTs) and 83 fasting plasma glucose determinations were made over a maximum 4-yr period before diabetes. The 5 prediabetic relatives (not diabetic when initially studied but subsequently progressed to overt diabetes) as a group showed a progressive rise in fasting glucose (r = 0.58, P less than 0.001, slope = 23.1 mg.dl-1.yr-1) and glucose at 60 min in IVGTT (r = 0.46, P = 0.01, slope = 47.5 mg.dl-1.yr-1) beginning 1.5 yr before diabetes. During the 4.0- to 1.5-yr period before overt diabetes, no change was observed in fasting glucose or glucose at 60 min on IVGTT (fasting glucose: r = 0.21, P = 0.18, slope = 2.1 mg.dl-1.yr-1; 60-min glucose: r = 0.08, P = 0.72, slope = 2.9 mg.dl-1.yr-1). The positive predictive value for a fasting glucose greater than 108 mg/dl to be within 1.5 yr of diabetes was 100% (11 of 11 values). The negative predictive value of a stimulated insulin (1-min + 3-min insulin - 2 X basal insulin) level greater than 24 microU/ml to be greater than 1.5 yr from diabetes was 90% (9 of 10 values) and 100% (10 of 10 values) at greater than 1 yr from overt diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)

Type I diabetes mellitus: a predictable autoimmune disease with interindividual variation in the rate of beta cell destruction

A large body of data generated during the past two decades has led to the ability to predict the development of Type I diabetes in the majority of relatives of diabetics. In particular we have recently proposed a dual parameter linear model to aid in predicting the onset of diabetes [years to diabetes = 1.5 + .03(IVGTT insulin secretion) - 0.008 (concn of insulin autoantibodies)]. The concentration of insulin autoantibodies in prediabetics appears to remarkably correlate with the age at which diabetes develops and the rate at which islet cell antibody-positive individuals progress to diabetes. Children developing diabetes before Age 5 often express more than 1000 nU/ml of such antibodies with the upper limit of normal of 39 nU/ml. Each prediabetic appears to be set at a characteristic level of insulin autoantibodies which does not consistently vary prior to the development of diabetes. During the prodromal phase preceding diabetes first phase insulin secretion is progressively lost, and the combination of insulin release which appears to reflect beta cell damage and the level of insulin antibodies accounts for more than 75% of the variation in time to diabetes over a 6-year interval. A subset of NOD mice also expresses insulin autoantibodies, and in addition essentially all NOD mice, but not F1 crosses of NOD by BALB/c, have antibodies to a target antigen of a RIN islet line protein (termed "polar antibodies"). In addition patients but not NOD mice have cytoplasmic islet cell antibodies which appear to react with a glycolipid islet target antigen. In the NOD mice the inheritance of disease is multigenic with a gene on chromosome 9, linked to the T cell marker theta, determining the bulk of islet cell destruction. In crosses of NOD mice with a series of normal strains, inheritance overt diabetes is correlated with inheritance of the NOD's unique I-A beta gene, though the bulk of islet destruction and insulitis can occur independent of MHC inheritance. Until the additional genes outside of the MHC, associated with the development of Type I diabetes, are identified for man, the NOD mouse, and the BB rat, one can only speculate concerning pathogenic mechanisms. To date islet cell destruction appears to be independent of polymorphic genes acting at the level of the islet target, and crucially dependent upon bone marrow precursor cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Genetic relationships between type I and type II diabetes mellitus

We propose that at least certain subsets of Type I and Type II diabetes share factor(s) responsible for genetic susceptibility. The data presented here to support this contention include: 1. A significantly increased cumulative risk (CR40) to age 40 for Type I diabetes in sibs of probands in families with a Type II diabetic parent (Type II diabetic parent: CR40-24.7 +/- 10.7%; normal parent: CR40 = 7.5 +/- 2.0%, x2 = 12.8, p less than 0.0005). 2. The relative risk (RR) for HLA DR4 in Type I diabetic probands with a Type II diabetic parent is higher than in probands with normal parents (RR = 2.4). 3. The haptoglobin genotype 2-2 is increased in Type I diabetics with Type II parents and the sharing of both HLA and haptoglobin haplotypes in affected sib pairs is distorted with an excess sharing of both haplotypes.

Hereditary diabetes in the KK mouse: an overview

Table III compares metabolic and morphologic characteristics of different species of control and KK mice. The C57BL/6J demonstrates no significant metabolic, clinical or histologic abnormalities. Our two highly inbred Swiss albino groups I and II also do not show significant glomerular lesions, although we found striking intolerance to glucose, hyperinsulinism, and obesity among them. Thus a genetic predisposition may be necessary in addition to various environmental factors to produce microangiopathy in KK mice. The yellow AY mouse is included in this table, since it is strikingly hyperinsulinemic and obese without concomitant vasculopathy such as the other mentioned control strains have. In conclusion, the KK mice develop chemical diabetes preceded by a stage of prediabetes and also demonstrate renal, retinal and neurologic complications similar to those seen in human diabetes. Of particular interest is the development of mild to moderate glomerulosclerosis in the prediabetic stage; with progression to severe glomerulosclerosis and attendant proteinuria later in life. With proper back-crossing, both hyperglycemia and glomerulosclerosis can be transmitted to normal control mice, suggesting that a specific genetic background is necessary for the development of diabetes and diabetic-like microangiopathy. We therefore suggest that the KK mouse serves as an ideal genetic animal for the study of non-insulin-dependent diabetes mellitus and its complications for rational prevention and therapy.

Diagnosis of pre-type I diabetes

Islet cell antibodies were found in 71 of 1169 first-degree relatives (6.1%) from 448 families who had a proband with type I diabetes. Seven children have since become insulin dependent. All had islet cell antibodies and were followed up prospectively with measurement of first-phase insulin production during intravenous glucose tolerance testing. In this group the statistical probability of developing type I diabetes within 12 months with 95% confidence was found to be 59% to 100% when the first-phase insulin secretion was less than 25 microU/mL. The identification of the prediabetes time period should allow an opportunity for intervention in the underlying disease process to determine if the onset of type I diabetes can be altered.

Immunoreactivity to a 64,000 Mr human islet cell antigen in sera from insulin-dependent diabetes mellitus patients and individuals with abnormal glucose tolerance

Autoantibodies in sera from newly diagnosed insulin-dependent diabetes mellitus (IDDM) patients recognize a 64,000 Mr human islet cell antigen. The incidence of these antibodies was 86% in 28 insulin-dependent diabetes mellitus patients, 100% in seven first-degree relatives with abnormal glucose tolerance, 6% in 34 healthy individuals, 17% in 29 patients with Hashimoto's or Graves' disease, and 0% in five systemic lupus erythematosis patients. It is suggested that the 64,000 Mr human islet cell protein is the major target antigen of islet cell autoantibodies in insulin-dependent diabetes mellitus.

Progressive autoimmune beta cell insufficiency: occurrence in the absence of high-risk HLA alleles DR3, DR4

In a prospective screening program for type I diabetes mellitus, we identified a unique family in which several members (mother and three siblings) expressed an unusual set of HLA-DR alleles (DR2+, DR3/4-) and were in different phases of immunologically mediated islet beta cell dysfunction. Immunologic and/or clinical manifestations of type I diabetes were absent in all siblings not sharing both HLA haplotypes in common with the proband. This article illustrates: the clinical utility of prospective family screening for predictive markers, such as islet cell antibodies, progressive autoimmune beta cell destruction can occur in the absence of the "high-risk" alleles HLA-DR3 and DR4, and HLA identity with the proband, rather than specific HLA alleles, i.e., presence of DR3, DR4 and absence of DR2, is an essential factor.

Prediction of type 1 diabetes mellitus--a report on three cases

In three children (patients 1, 2 and 3) insulin-dependency was predicted 28, 32 and 4 months, respectively before the disease became clinically manifest, by the finding of islet cell antibodies at that time. These retrospective findings support the evidence for a long pre-diabetic phase in childhood diabetes, marked by the presence of islet cell antibodies, as well as the linkage of HLA-antigens to the susceptibility to this disease. The possibility of detecting pre-diabetic states in children before the endogenous insulin secretion decreases to the point of producing clinical symptoms support efforts by basic scientists to develop techniques for immunological intervention early in the course of the disease.

Prospective study of lymphocyte subsets in subjects genetically susceptible to type 1 (insulin-dependent) diabetes

A prospective study of lymphocyte subsets has been carried out for 18 months in 58 healthy first-degree relatives of Type 1 (insulin-dependent) probands. Subjects selected for presence or absence of islet cell antibodies included 10 with complement-fixing islet cell antibodies, 10 with conventional islet cell antibodies and 38 without islet cell antibodies. Immunoregulatory and effector lymphocytes subsets, and in particular activated T-cells, were investigated using a panel of monoclonal antibodies. The results showed no significant changes in total T, helper, suppressor/cytotoxic cell or K/NK cells. Activated T-cells were observed at least once in 22 subjects using the 4F2 monoclonal antibody and in 11 using the Tac antibody. Seven subjects had 4F2-positive cells on repeated occasions and one twice showed Tac-positive cells. Fluctuations and/or loss of islet cell antibodies were observed during follow-up. There was no correlation between presence of activated T-cells and either islet cell antibody status of HLA haplotype sharing with the diabetic proband. On the other hand, a significant correlation was observed between HLA-DR3 positivity of subjects and the occurrence of activated T-cells (both 4F2-positive and Tac-positive). We conclude that subjects with HLA-DR3 may be especially prone to T-cell activation. As none of the 'high risk' individuals developed diabetes in the course of follow-up, the relevance of these observations in the pathogenesis of Type 1 diabetes needs more prolonged investigation.

Pre-type 1 (insulin-dependent) diabetes: common endocrinological course despite immunological and immunogenetic heterogeneity

In an ongoing prospective study 32 individuals have been evaluated for insulin secretory dynamics, islet cell antibodies and HLA antigens, during the preclinical phase of Type 1 diabetes mellitus. Twenty-four out of the 32 subjects were islet cell antibody-positive. To date, 14 subjects (10 islet cell antibody-positive, four islet cell antibody-negative) have progressed to develop overt diabetes. Several patterns of HLA-DR expression were noted (DR3/DR4, DR3/DR3, DR3/x, DR3/DR1, DR4/x, DR4/DR7, DR5/DR7, DR1/DR7 and DR1/DR2). Irrespective of differences in islet cell antibody status or HLA-DR alleles, pre-diabetic individuals exhibited a similar slow course of progressive beta-cell dysfunction.

[Autosomal dominant mild juvenile diabetes mellitus (MODY) (author's transl)]

A family is described in which eleven members, over four generations, suffer from the autosomal dominant inherited maturity onset type diabetes of young people (MODY). A comparison of these findings with those of six families previously described in the literature shows in particular that: 1. manifestation of the disease is predominantly at a fairly young age, 2. the complaint is not insulin-dependent nor is it progressive, 3. when medical supervision is adequate, there are hardly any secondary complications, 4. the inheritance pattern is autosomal dominant with high penetrance and probably a stronger expressivity in the female. This disease can be separated from the classical, insulin-dependent diabetes of the young, from the autosomal dominant lipatrophic diabetes and from the heterozygous form of the autosomal recessive complaint, which in the homozygous state shows diabetes mellitus and insipidus with optic atrophy.

[Relationship between the results of glucose tolerance test and plasma content of immunoreactive insulin in the relatives of patients with juvenile form of diabetes mellitus]

Relatives (67) of patients with a juvenile form of diabetes mellitus and in 17 persons of control group were investigated. Hyperinsulinemia was revealed in close relatives and in persons with adiposity. The highest insulin response to glucose load was in persons with "doubtful" glucose tolerance test results. Insulinemic curve was flattened in the group of persons with latent and particularly with manifest diabetes. On the basis of the results obtained and the literature data a conclusion was drawn that hyperinsulinemia was one of the significant indices of disturbances in the regulation of insulin secretion in persons with hereditary aggravation by diabetes mellitus and could serve as a diagnostic index of the early stages of this disease.

Effect of continuous low-dose insulin treatment on subsequent incidence of diabetes in genetically prediabetic Chinese hamsters

In an attempt to prevent the onset of diabetes, young, genetically prediabetic (but not yet hyperglycemic) Chinese hamsters were treated continuously with insulin via minipump for 4 wk beginning 1 wk before the predicted age of onset of glucosuria (age 7 wk). Continuous insulin infusion which increased the plasma insulin levels by 70%, did not cause hypoglycemia, nor did it reduce the incidence or severity of diabetic symptoms over the ensuing year of observation. In fact, early treatment with exogenous insulin tended to cause increased hyperglycemia and glucosuria. No plasma anti-insulin antibodies were detected 3 and 9 months after stopping insulin treatment.

Diabetes mellitus and genetic prediabetes. Decreased replicative capacity of cultured skin fibroblasts

The idea that the gene(s) that cause diabetes mellitus can be expressed in extrapancreatic cells has been examined by tissue culture techniques. Skin biopsies were obtained from 25 normal subjects (N), 26 overt diabetics (D), 16 of juvenile onset (JOD) and 9 of maturity onset (MOD), and 21 subjects genetically predisposed to diabetes (P) on the basis of maturity-onset diabetes in both parents. Each biopsy was subdivided, multiple skin fragments were explanted in vitro, and several parameters of cellular outgrowth were monitored in primary and secondary cultures until cell division ceased because of senescence. In general, the rank order of growth vigor was N greater than P greater than D although differences were often marginal and statistically significant between N and JOD and(or) MOD. Outgrowth of epithelial cells was more vigorous in N explants in early stages, but later, JOD and MOD cells grew better than those of N. Outgrowth of fibroblast cells from N explants was more vigorous both at early and later stages and required less time to achieve maximum percent outgrowth. In secondary cultures, N cells grew faster than the other three groups so that fewer days elapsed between subcultures but significant differences were only seen between N and one or two of the other groups over some of the first seven subcultures. The onset of cellular senescence occurred earlier in P and JOD cultures both in mean population doublings and calendar time. N cultures had a higher percent surviving clones after picking than MOD, and a shorter recloning time than clones of JOD. The replicative life-spans of cultures (mean population doublings +/- SE) were N = 52.54 +/- 2.24, P = 47.84 +/- 2.43, JOD = 47.12 +/- 2.99, and MOD = 46.40 +/- 4.04, but differences did not reach significance for N vs the other three groups. The data demonstrate that cellular growth is impaired in both JOD and MOD types of cultures and to a generally lesser extent in P cultures. This is consistent with intrinsic genetic defects but the possibility that persistent deleterious effects of in vivo pathophysiology contribute alone or in combination cannot be ruled out. Therefore, the diabetic defect(s) can be expressed in extrapancreatic cells of mesenchymal origin. This system should prove useful in exploring the interplay between genetic and environmental factors in diabetes, the mechanisms(s) of hyperglycemia and other metabolic derangements, and the propensity that affected individuals have to develop degenerative diseases.

Unexplained hyperinsulinemia in normal and "prediabetic" Pima Indians compared with normal Caucasians. An example of racial differences in insulin secretion

The pattern of insulin response to oral and/or intravenous glucose has been claimed to be characteristic of diabetes and even prediabetes. To determine if differences in insluin secretion might explain the exceptionally high prevalence of diabetes in the Pima Indians, 26 genetically normal Pimas (nondiabetic offspring of nondiabetic parents), 32 genetically prediabetic Pimas (nondiabetic offspring of diabetic parents), 10 diabetic Pimas, and 29 normal Caucasians were studied. All subjects received an intravenous glucose tolerance test (IVGTT) to examine the acute-phase insulin response, and all nondiabetic subjects received an oral glucose tolerance test (OGTT) and arginine infusion (AI). The prediabetics also received a cortisone-primed oral glucose tolerance test (CGTT) and were classified by the result of this test. While acute-phase insulin release during the IVGTT was absent in the diabetics, there was a rapid response in all nondiabetics. Prediabetic Pimas with normal or abnormal CGTT had insulin levels similar to normal Indians during the IVGTT, OGTT, and AI. Thus, no evidence of impairment of acute- or late-phase insulin release was found. The normal and prediabetic Indians had fasting and stimulated insulin levels during all the tests two-to-threefold greater than the Caucasians. Differences in insulin levels between the two races could not be explained by differences in glucose level, age, or obesity.

Serum insulin response to slow-rise glucose infusion in "genetic prediabetics" (offspring of two diabetic parents)

The insulin response to a programed slow-rise glucose infusion designed to mimic the postprandial rise in glucose was studied in five offspring of two diabetic parents (ODP) and seven normal subjects. The ODP had higher mean blood glucose levels towards the end of the infusion and during the postinfusion period. The rates of glucose disappearance calculate during the postinfusion period were comparable in the two groups. Despite the apparent similarity of serum insulin levels of ODP and normal subjects, the amount of insulin secreted per unit of glycemic stimulus was lower in the ODP group. When the glucose infusion test was preceded by an acute load of glucose, similar findings in the insulin secretory dynamics were found in the ODP group. These data suggest that an impairment in insulin secretion exists in ODP when they are challenged by the slow rise of blood glucose achieved by this type of an intravenous glucose infusion.

Lipid, glucose, and insulin interrelationships in normal, prediabetic, and chemical diabetic subjects

Fasting levels of plasma cholersterol and triglyceride, lipoprotein patterns, and fasting and postintravenous glucose levels of blood glucose, serum insulin, serum growth hormone, and plasma free fatty acids in a genetic potential diabetic population were compared to those in a similar normal control population. THe potential diabetic population was further divided into groups of patients with a normal (prediabetic) or abnormal (chemical diabetic) glucose tolerance test. Although no clear-cut lipid differences were noted, certain trends appeared. More type IV hyperlipoproteinemia was seen in male prediabetic (21%) and male chemical diabetic patients (19%) than in normal male subjects (5%); in female subjects only a few type IV patterns were seen. Type II hyperlipoproteinemia was not seen in any normal subject, but was noted in nearly 9% of those with chemical diabetes. Fasting cholesterol levels correlated better with age than did fasting triglyceride levels in most of the patient groups. Fasting triglyceride levels showed a significant positive correlation with the serum insulin area of the oral glucose tolerance test in the normals wna prediabetic persons, and also showed a significant positive correlation with the blood glucose area of the prediabetic and chemical diabetic patients. It is suggested that a normal relationship between triglyceride concentration and insulin response to glucose is lost in chemical diabetes. Sex differences were also noted in the inslin response and the insulin-glucose relationships during the oral glucose tolerance test, with normal menstruation women showing a significantly lower insulin-glucose relationship than the age-related men.