Decreased growth velocity before IDDM onset.

Diabetes can retard growth. Growth was studied prospectively in 12 nondiabetic identical twins aged less than 14 yr and in their co-twins with insulin-dependent diabetes mellitus (IDDM) to determine whether changes in growth occur before the onset of IDDM. Seven of the 12 nondiabetic twins subsequently developed IDDM; the remainder are now unlikely to become diabetic. A significantly reduced growth velocity was observed more frequently in the nondiabetic twins (7 of 12) than in their diabetic co-twins (1 of 12; P = 0.03). Of the 7 nondiabetic twins who were prediabetic, 6 had a reduction in growth velocity to below the 3rd percentile before the onset of diabetes compared with 1 of their diabetic co-twins (P = 0.03). However, only 1 of the 5 nondiabetic twins who did not develop diabetes showed a reduction in growth velocity. The nadir of growth in the twins who developed diabetes occurred a mean of 1.2 yr before diagnosis (range 0.3-2.3 yr). All 7 of the prediabetic twins had islet cell antibodies when first seen, and 3 had them before they showed either decreased growth velocity or impaired glucose tolerance. In 4 prediabetic twins, the decreased growth preceded impaired glucose tolerance. The prediabetic twins tested had lower testosterone or estradiol levels at the time they showed decreased growth than their diabetic twins. We conclude that decreased growth velocity is an early sensitive marker of IDDM.

Alterations in T-lymphocyte subpopulations in type I diabetes. Exploration of genetic influence in identical twins.

To evaluate factors influencing the alteration in subsets of T-lymphocytes, we studied 24 pairs of identical twins discordant for insulin-dependent (type I) diabetes mellitus. Subsets were assessed by monoclonal antibodies and a pure preparation of peripheral blood mononuclear cells obtained by centrifugation of heparinized whole blood with a Ficoll/Triosil gradient. In 12 pairs studied within 5 yr of diagnosis, we observed a reduction in the percentage of cells reacting with OKT8 (recognizing the CD8 antigen present on the suppressor/cytotoxic subset) (P less than .05), but a similar level was detected in their nondiabetic cotwins. In 12 pairs studied greater than 5 yr after the diagnosis and in whom the nondiabetic twin is less likely to develop diabetes, the percentage of cells reacting with OKT8 was reduced in both the diabetic (P less than .05) and the nondiabetic (P less than .01) twins. Reductions were also seen with OKT3 (recognizing the CD3 antigen present on the total T-lymphocyte population) and OKT4 (recognizing the CD4 antigen present on the helper/inducer subset), but only in the diabetic twins from the group with longer discordance. We conclude that a reduced percentage of suppressor/cytotoxic cells is associated with type I diabetes, but the reduction appears to be genetically determined. Total T-lymphocytes are also reduced but mainly in the helper/inducer subset and only in diabetic patients of long duration. Such a reduction cannot therefore be primarily genetically determined.

A novel polymorphism in the 5' flanking region of the glucose transporter (GLUT1) gene is strongly associated with diabetic nephropathy in patients with Type 1 diabetes mellitus.

Glucose transporter 1 (GLUT1) activity has been implicated in renal hypertrophy and extracellular matrix formation in mesangial cells. Recent studies have suggested that polymorphisms in the GLUT1 gene are associated with susceptibility to diabetic nephropathy (DN) in patients with diabetes mellitus. In this study, a novel polymorphism (A-2841T) in the 5' flanking region of GLUT1 was examined in 288 patients with Type 1 diabetes mellitus (T1DM) and 101 normal controls. The polymorphisms were amplified and the fragment digested with the enzyme HpyCH4V. There was a highly significant increase in the frequency of the TT-2841 genotype in patients with nephropathy (n=131) compared with those with either no microvascular complications after a 20-year duration of diabetes (uncomplicated; n=72; 54.5% vs. 2.7%, chi=79.4, P<.000001). There was no difference between the uncomplicated group and those who only had retinopathy (n=50; 2.7% vs. 4.0%, respectively). The frequency in recently diagnosed patients was 17.1% and only 2.0% in normal controls. In contrast, the AA genotype was found in 13.6% of the nephropaths, 76.3% of uncomplicated, 48.0% of retinopaths, and 65% of normal controls. These results confirm previous reports of an association between the GLUT1 gene and susceptibility to DN but not retinopathy. The localisation of this polymorphism suggests that it may be involved in the expression of the gene.

A polymorphism in the promoter region of the gene for interleukin-6 is associated with susceptibility to type 1 diabetes mellitus.

Type 1 diabetes mellitus is an autoimmune disease characterized by the destruction of the insulin-producing islet beta cells. It is likely that several genetic and environmental factors contribute to this process. There is increasing evidence showing that polymorphisms in cytokine genes may play an important role in modifying the immune response. Interleukin-6 (IL-6) is a cytokine that has been implicated in a number of immune-mediated diseases. Further, there is a polymorphism at position -174 (G(-174)C) of the promoter region of the IL-6 gene that may alter the expression of the gene. In this study, the G(-174)C polymorphism was investigated in 257 Caucasoid patients with type 1 diabetes, 53 two-parent-proband trios, and 120 normal, healthy controls. DNA was amplified using amplimers that flank the G(-174)C site, and the products were digested with the restriction endonuclease NlaIII to detect the G or the C allele. The homozygous G,G(-174) genotype was increased in the patients compared with the normal controls (50.6% vs. 33.3%, p < 0.002), with a decrease in the C,C genotype in the patients compared with the controls (12.5% vs. 24.2%, respectively, p < 0.004). In the 53 trios studied, the G allele was transmitted in 29 of 53 informative meioses. There was no association with age at onset of diabetes or the presence of diabetic complications. In conclusion, these results suggest that the IL-6 gene may contribute to the genetic susceptibility to type 1 diabetes.

The HLA-E locus is associated with age at onset and susceptibility to type 1 diabetes mellitus.

Previous studies have suggested that the human leukocyte antigen (HLA) class I region may be involved in determining the age at onset and clinical severity of type 1 diabetes. We have investigated the frequency of polymorphisms of the nonclassical HLA class I gene, HLA-E, in 199 British Caucasian patients with type 1 diabetes and 82 healthy controls. A highly significant increase in the frequency of the HLA-E 0101 genotype was found in the patients compared to controls (chi(2) = 15.3, p < 0.00009). The frequency of the HLA-E 0101 genotype was increased in those patients diagnosed after 10 years of age, while the frequency of the 0101, 0103 genotype was significantly increased in those subjects diagnosed before 10 years of age (chi(2) = 26.0 p < 0.000003 and chi(2) = 13.0 p < 0.0003, respectively). No obvious interaction between the HLA-E locus and the class II DQB1*0201, 0302, and 0501 susceptibility alleles was found. This is the first report of an association between the HLA-E locus and susceptibility to an autoimmune disease.

Immunoglobulin constant heavy chain gene polymorphisms of Caucasoids of west European origin.

We have used restriction fragment length polymorphism (RFLP) analysis to investigate the immunoglobulin constant heavy chain (IgCH) loci and the associated locus Dl4Sl, of Caucasoids from South East England and South-West. West Germany, Haplotypes were determined using probes to the Ig heavy chain switch loci S mu and S alpha 1, the IgC gamma 3 and IgC gamma 2 loci as well as the Dl4Sl locus which is 3' of the IgCH loci. The 6.3:1.7 kilobase (kb) Bst EII C gamma 3-C gamma 2 haplotype was the most prevalent in the population from South-East England (frequency 0.364), whilst the 2.3:3.7 kb C gamma 3-C gamma 2 haplotype was the major haplotype in the German population (frequency 0.400). With one exception, the major haplotypes of these two populations differed from the ones previously published for a Caucasoid population from California. This suggests that there may be a major ancestral IgCH haplotype which has been maintained in the population, whilst other haplotypes tend to be specific for a particular group of Caucasoids.

Are thyrogastric autoantibodies associated with an increased susceptibility to developing type 1 (insulin-dependent) diabetes? A study in identical twins.

To examine whether the presence of thyrogastric autoantibodies is associated with an increased susceptibility towards developing type 1 diabetes we have tested for thyroid (microsomal and thyroglobulin) and gastric-parietal cell antibodies in 86 pairs of identical twins, 47 discordant and 39 concordant for type 1 diabetes. Autoantibodies were detected in both twins of a pair in 35 and in neither twin in 45 pairs. In only 6 pairs (3 discordant) was there a discrepancy in the antibody results between co-twins. The frequency of antibodies was similar in twin pairs discordant, (21/44, 48%), and concordant, (14/36, 39%), for diabetes. Thyrogastric antibodies were not more frequent in pairs that were female, diagnosed above the age of 20, or had HLA DR3 as opposed to DR4. We conclude that thyrogastric autoantibodies are common in both type 1 diabetic patients and their non-diabetic identical twins. Their presence appears to be genetically determined but does not increase the susceptibility of developing diabetes. The presence of autoantibodies does not appear to indicate a separate aetiological type of diabetes.

Low serum haemolytic function of the fourth complement component (C4) in insulin dependent diabetes.

Low serum concentrations of the fourth component of complement (C4) are found in insulin dependent diabetes, and may be important in the aetiology of the disease. To ascertain whether function of C4 is also impaired both its haemolytic activity and its concentration were measured in 34 insulin dependent diabetics, 15 non-insulin dependent diabetics, 20 healthy subjects, and 12 pairs of monozygotic twins discordant for insulin dependent diabetes. C4 function was measured by a radial immune haemolytic assay, and C4 concentration by laser nephelometry. Both measurements were significantly lower in insulin dependent diabetics (C4 function: median 47%, range 4-100%; C4 concentration: 0.22 g/l, 0.10-0.38 g/l) than in non-insulin dependent diabetics (67%, 33-138%, p less than 0.01; 0.27 g/l, 0.16-0.50 g/l, p less than 0.02) and controls (74%, 33-138%, p less than 0.01; 0.27 g/l, 0.18-0.40 g/l, p less than 0.03). C4 function and concentration were lower in both diabetic (48%, 12-100%; 0.17 g/l, 0.08-0.31 g/l) and non-diabetic twins (47%, 12-100%; 0.17 g/l, 0.07-0.36 g/l) than controls (p less than 0.01; p less than 0.01). Thirteen (38%) of the insulin dependent diabetics had a reduction in either C4 function or concentration, but in only five were both features reduced. Values of function and concentration were strongly correlated in both diabetic and non-diabetic twins (r = 0.95, p less than 0.001; r = 0.92, p less than 0.001). These results show defects in C4 function and concentration in insulin dependent diabetes, which--being present in the non-diabetic co-twin of diabetics--may represent a genetic predisposition to the disease.

Chromosome 7q35 and susceptibility to diabetic microvascular complications.

Aldose reductase (ALR2), the first enzyme of the polyol pathway, may plan an important role in the pathogenesis of diabetic microvascular complications. The gene coding for ALR2 has been localized to chromosome 7q35. Using an ALR2 probe in conjunction with the restriction endonuclease Bam-HI, we have investigated the ALR2 locus of 128 patients with type I diabetes. A significant decrease in the frequency of the 8.2 kilobase (kb) Bam-HI ALR2 genotype and 8.2 kb allele was found in patients with nephropathy (nephropaths) compared to those with retinopathy alone (retinopaths) (p < 0.05 and 0.25, respectively). We have previously shown that an RFLP of the T-cell antigen receptor constant beta-chain (TCRBC) locus, which is also localized to chromosome 7q35, is strongly associated with susceptibility to microvascular complications. The 128 patients were genotyped using the restriction endonuclease Bgl-II and a TCRBC probe. The 10/9.2-8.2 kb TCRBC-ALR2 genotype was significantly decreased in the nephropaths compared to the retinopaths (13.7% versus 43.6%, chi 2 = 10.1, p < 0.0025). The 10/9.2 and 9.2/9.2 kb TCRBC-ALR2 haplotypes were increased in the nephropaths compared to the retinopaths (32.5% versus 8.9% chi 2 = 10.9, p < 0.001). These results suggest that chromosome 7q35 harbors a gene(s) that is involved in the pathogenesis of microvascular complications. Interestingly, the gene coding for endothelial nitric oxide synthase has recently been localized to the same chromosomal region as ALR2.

The angiotensin I-converting enzyme (ACE) locus is strongly associated with age and duration of diabetes in patients with type I diabetes.

We have investigated the frequency of the angiotensin I-converting enzyme (ACE) insertion/ deletion (I/D) polymorphism in 249 patients with type I diabetes and 162 normal healthy controls. There was no significant difference in the frequency of ACE genotypes between those patients with diabetic nephropathy (n = 72) (nephropaths) compared to those with no proteinuria after 20 years duration of diabetes (n = 86) (normoalbuminurics). There was, however, a significant difference in the frequency of ACE genotypes between the short-duration and long-term normoalbuminuric group (chi = 11.5, p = 0.001). Analysis of the ACE genotypes with respect to age and duration of diabetes showed that homozygosity for the insertion (I/I) genotype was significantly decreased with longer duration of diabetes (r2 = 92.7%, p < 0.009). No association was found with age in the normal controls. In conclusion, these results suggest that the ACE locus may be associated with longevity and survival in patients with type I diabetes rather than diabetic nephropathy or microvascular disease per se.

Patients' attitudes towards screening for diabetes and other medical conditions in the dental setting.

AIM: To determine the attitudes of patients attending routine appointments at primary care dental clinics and general dental practices towards the possibility of chair-side screening for medical conditions, including diabetes, in the dental setting. METHODS: A brief, anonymous, self-administered questionnaire distributed to adult patients (≥18 years) attending 2 primary care dental clinics and 16 general dental practices in South-West England. RESULTS: One hundred and ninety-seven completed questionnaires were received from patients at primary care dental clinics and 429 from general dental practice patients. Overall, 87% of respondents thought that it was important or very important that dentists screened patients for medical conditions such as diabetes; 79% were very willing to let a dental team member carry out screening. The majority indicated willingness to be screened for various medical conditions during a visit to the dentist, with significantly higher proportions of respondents in the primary care clinics indicating willingness (hypertension: 83% vs 74%; heart disease: 77% vs 66%; diabetes 82% vs 72% [all p <0.02]). Nearly two thirds of primary care clinic respondents and over half of general practice patients indicated that they would be willing to discuss test results with the dental team. Overall, 61% had never knowingly been screened or tested for diabetes; 20% reported that they had been tested within the previous 12 months. CONCLUSION: The majority of respondents supported the concept of medical screening in a dental setting and were willing both to have screening tests and discuss their results with the dental team. Patient acceptance is paramount for successful implementation of such screening programmes.

Genetic association analyses of non-synonymous single nucleotide polymorphisms in diabetic nephropathy.

AIMS/HYPOTHESIS: Diabetic nephropathy, characterised by persistent proteinuria, hypertension and progressive kidney failure, affects a subset of susceptible individuals with diabetes. It is also a leading cause of end-stage renal disease (ESRD). Non-synonymous (ns) single nucleotide polymorphisms (SNPs) have been reported to contribute to genetic susceptibility in both monogenic disorders and common complex diseases. The objective of this study was to investigate whether nsSNPs are involved in susceptibility to diabetic nephropathy using a case-control design. METHODS: White type 1 diabetic patients with (cases) and without (controls) nephropathy from eight centres in the UK and Ireland were genotyped for a selected subset of nsSNPs using Illumina's GoldenGate BeadArray assay. A chi (2) test for trend, stratified by centre, was used to assess differences in genotype distribution between cases and controls. Genomic control was used to adjust for possible inflation of test statistics, and the False Discovery Rate method was used to account for multiple testing. RESULTS: We assessed 1,111 nsSNPs for association with diabetic nephropathy in 1,711 individuals with type 1 diabetes (894 cases, 817 controls). A number of SNPs demonstrated a significant difference in genotype distribution between groups before but not after correction for multiple testing. Furthermore, neither subgroup analysis (diabetic nephropathy with ESRD or diabetic nephropathy without ESRD) nor stratification by duration of diabetes revealed any significant differences between groups. CONCLUSIONS/INTERPRETATION: The nsSNPs investigated in this study do not appear to contribute significantly to the development of diabetic nephropathy in patients with type 1 diabetes.

Is neighbourhood deprivation a risk factor for gestational diabetes mellitus?

AIMS: To assess the relationship between neighbourhood deprivation and the rate of gestational diabetes mellitus (GDM) using routinely collected data from a clinical information system, in Plymouth, UK. METHODS: Between 1 January 1996 and 31 December 1997, 3933 women residing within the Plymouth Primary Care Trust (PCT) were screened for GDM using indices of neighbourhood deprivation and prevalence of GDM. Areas (n = 43) were classified according to the Townsend index, measuring material deprivation. Pregnant women with and without GDM were compared. RESULTS: The prevalence of GDM was 1.7%[95%, confidence interval (CI) 1.20, 2.11]. The prevalence of GDM ranged from 1.05% (95% CI 0.60, 1.70) in the most deprived to 2.10% (95%, CI 1.34, 3.13), in the least deprived neighbourhood. Crude rates decreased by 50%[relative prevalence (RP) (95% CI) 0.50 (0.27, 0.94); P = 0.06] amongst those living in the most-deprived compared with those living in the least-deprived areas. Using a stepwise binary logistic regression model, older age at delivery significantly increased the risk of developing GDM. [RP (95%, CI) 1.09, (1.04, 1.13)]. Townsend deprivation score had no significant independent association with GDM when other covariates were considered. CONCLUSION: These data suggest that the neighbourhood context in which women live has no impact on the risk of GDM. Diabet.

Maternal glucose levels influence birthweight and 'catch-up' and 'catch-down' growth in a large contemporary cohort.

AIM: To explore the effects of maternal glucose on birthweight, infant and childhood growth in non-diabetic pregnant women using routinely collected data. METHODS: Routinely collected data were extracted retrospectively from two clinical databases. These data comprised measurements of maternal random plasma glucose, infant birthweight, infant and child weight and height at 6-8 weeks, 24-36 weeks and 96-120 weeks in 6263 cases. After data cleaning, 4681 were analysed. RESULTS: When the data were analysed in thirds, a positive association between birthweight standard deviation scores (SDS), weight SDS and height SDS with maternal random plasma glucose (RPG) was observed. Regression analysis of birthweight SDS and RPG was significant (P < 0.001). Babies were approximately 48 g heavier at birth for each 1 mmol/l increase of mother's RPG. Infants who showed 'catch-up' growth (as shown by change in weight SDS) at 2 years were born to mothers with lower glucose levels than infants who showed 'catch-down' growth (P < 0.001). CONCLUSIONS: Random maternal glucose concentrations (taken at 28 weeks' gestation) in the normal range are positively related to birthweight. Glucose concentrations also predict greater weight and length in infancy. Despite this, babies born to mothers with higher glucose concentrations within the normal range show significant 'catch-down' growth in infancy as shown by a fall in weight SDS.

Short-term effects of severe dietary carbohydrate-restriction advice in Type 2 diabetes--a randomized controlled trial.

OBJECTIVE: This study sought to examine the effects of a 3-month programme of dietary advice to restrict carbohydrate intake compared with reduced-portion, low-fat advice in obese subjects with poorly controlled Type 2 diabetes. RESEARCH DESIGN AND METHODS: One hundred and two patients with Type 2 diabetes were recruited across three centres and randomly allocated to receive group education and individual dietary advice. Weight, glycaemic control, lipids and blood pressure were assessed at baseline and 3 months. Dietary quality was assessed at the end of study. RESULTS: Weight loss was greater in the low-carbohydrate (LC) group (-3.55 +/- 0.63, mean +/- sem) vs. -0.92 +/- 0.40 kg, P = 0.001) and cholesterol : high-density lipoprotein (HDL) ratio improved (-0.48 +/- 0.11 vs. -0.10 +/- 0.10, P = 0.01). However, relative saturated fat intake was greater (13.9 +/- 0.71 vs. 11.0 +/- 0.47% of dietary intake, P < 0.001), although absolute intakes were moderate. CONCLUSIONS: Carbohydrate restriction was an effective method of achieving short-term weight loss compared with standard advice, but this was at the expense of an increase in relative saturated fat intake.

Polymorphisms of the glucose transporter (GLUT1) gene are associated with diabetic nephropathy.

BACKGROUND: Diabetic nephropathy (DN) is a major cause of morbidity and mortality in patients with type 1 diabetes mellitus. Recent studies suggest that genetic factors, including polymorphisms in the flanking region of the aldose reductase gene (5'ALR2), play an important role in the pathogenesis of nephropathy. Glucose transporter (GLUT1) activity has been implicated in renal hypertrophy and extracellular matrix formation in mesangial cells. The aim was to investigate the frequency of a polymorphism within the GLUT1 gene in 186 Caucasoid patients with type 1 diabetes and 104 normal controls. METHODS: Amplimers flanking the Xba-I polymorphic site in the second intron were employed to amplify DNA from subjects. The amplified DNA was restricted with endonuclease Xba-I, separated by gel electrophoresis, and visualized. In the absence of an Xba-I site, a fragment of 1.1 kilobase was seen, whereas fragments of 0.9 and 0.2 were generated if the Xba-I site was present. RESULTS: There was a highly significant increase in the frequency of the 1.1 allele in those patients with nephropathy (N = 70) compared with those with no proteinuria or retinopathy after 20 years of diabetes (uncomplicated N = 44, 61.4 vs. 40.9%, respectively, P < 0.001). The 1.1/1.1 genotype was also significantly increased in the nephropathy group compared with the uncomplicated group of patients (37.1 vs. 13.6%, respectively, P < 0.01). The frequency of the 1.1/1.1 genotype was similar in 30 patients with retinopathy but not nephropathy when compared with the uncomplicated group of patients (13.6 vs. 16.7%). Furthermore, only 8 out of 49 patients with DN had the Z+2 5'ALR2 DN "protective" allele and the 0.9 GLUT1 allele in contrast to 21 out of 39 uncomplicated patients (P < 0.0002). CONCLUSION: These results suggest that the GLUT1 gene together with the aldose reductase gene are associated with susceptibility to DN in patients with type 1 diabetes.