Study Protocol: The Norfolk Diabetes Prevention Study [NDPS]: a 46 month multi - centre, randomised, controlled parallel group trial of a lifestyle intervention [with or without additional support from lay lifestyle mentors with Type 2 diabetes] to prevent transition to Type 2 diabetes in high risk groups with non - diabetic hyperglycaemia, or impaired fasting glucose.

BACKGROUND: This 7 year NIHR programme [2011-2018] tests the primary hypothesis that the NDPS diet and physical activity intervention will reduce the risk of transition to type 2 diabetes (T2DM) in groups at high risk of Type 2 diabetes. The NDPS programme recognizes the need to reduce intervention costs through group delivery and the use of lay mentors with T2DM, the realities of normal primary care, and the complexity of the current glycaemic categorisation of T2DM risk. METHODS: NDPS identifies people at highest risk of T2DM on the databases of 135 general practices in the East of England for further screening with ab fasting plasma glucose and glycosylated haemoglobin [HbA1c]. Those with an elevated fasting plasma glucose [impaired fasting glucose or IFG] with or without an elevated HbA1c [non -diabetic hyperglycaemia; NDH] are randomised into three treatment arms: a control arm receiving no trial intervention, an arm receiving an intensive bespoke group-based diet and physical activity intervention, and an arm receiving the same intervention with enhanced support from people with T2DM trained as diabetes prevention mentors [DPM]. The primary end point is cumulative transition rates to T2DM between the two intervention groups, and between each intervention group and the control group at 46 months. Participants with screen detected T2DM are randomized into an equivalent prospective controlled trial with the same intervention and control arms with glycaemic control [HbA1c] at 46 months as the primary end point. Participants with NDH and a normal fasting plasma glucose are randomised into an equivalent prospective controlled intervention trial with follow up for 40 months. The intervention comprises six education sessions for the first 12 weeks and then up to 15 maintenance sessions until intervention end, all delivered in groups, with additional support from a DPM in one treatment arm. DISCUSSION: The NDPS programme reports in 2018 and will provide trial outcome data for a group delivered diabetes prevention intervention, supported by lay mentors with T2DM, with intervention in multiple at risk glycaemic categories, and that takes into account the realities of normal clinical practice. TRIAL REGISTRATION: ISRCTN34805606 (Retrospectively registered 16.3.16).

Intervention fidelity assessment: A sub-study of the Norfolk Diabetes Prevention Study (NDPS).

BACKGROUND: Previous research has shown that lifestyle modification can delay or prevent the onset of type 2 diabetes in high-risk individuals. The Norfolk Diabetes Prevention Study (NDPS) was a parallel, three-arm, randomized controlled trial with up to 46 months follow-up that tested a group-delivered, theory-based lifestyle intervention to reduce the incidence of type 2 diabetes in high-risk groups. The current study aimed to evaluate if the NDPS intervention was delivered to an acceptable standard and if any part(s) of the delivery required improvement. METHODS: A sub-sample of 30, 25 for inter-rater reliability and audio-recordings of the NDPS intervention education sessions were assessed independently by two reviewers (CT, TW) using a 12-item checklist. Each item was scored on a 0-5 scale, with a score of 3 being defined as 'adequate delivery'. Inter-rater reliability was assessed. Analysis of covariance (ANCOVA) was used to assess changes in intervention fidelity as the facilitators gained experience. RESULTS: Inter-rater agreement was acceptable (86%). A mean score of 3.47 (SD = .38) was achieved across all items of the fidelity checklist and across all intervention facilitators (n = 6). There was an apparent trend for intervention fidelity scores to decrease with experience; however, this trend was non-significant (p > .05) across all domains in this small sample. CONCLUSION: The NDPS was delivered to an acceptable standard by all Diabetes Prevention Facilitators. Further research is needed to better understand how the intervention's delivery characteristics can be optimized and how they might vary over time.

Genetic evidence that raised sex hormone binding globulin (SHBG) levels reduce the risk of type 2 diabetes.

Epidemiological studies consistently show that circulating sex hormone binding globulin (SHBG) levels are lower in type 2 diabetes patients than non-diabetic individuals, but the causal nature of this association is controversial. Genetic studies can help dissect causal directions of epidemiological associations because genotypes are much less likely to be confounded, biased or influenced by disease processes. Using this Mendelian randomization principle, we selected a common single nucleotide polymorphism (SNP) near the SHBG gene, rs1799941, that is strongly associated with SHBG levels. We used data from this SNP, or closely correlated SNPs, in 27 657 type 2 diabetes patients and 58 481 controls from 15 studies. We then used data from additional studies to estimate the difference in SHBG levels between type 2 diabetes patients and controls. The SHBG SNP rs1799941 was associated with type 2 diabetes [odds ratio (OR) 0.94, 95% CI: 0.91, 0.97; P = 2 x 10(-5)], with the SHBG raising allele associated with reduced risk of type 2 diabetes. This effect was very similar to that expected (OR 0.92, 95% CI: 0.88, 0.96), given the SHBG-SNP versus SHBG levels association (SHBG levels are 0.2 standard deviations higher per copy of the A allele) and the SHBG levels versus type 2 diabetes association (SHBG levels are 0.23 standard deviations lower in type 2 diabetic patients compared to controls). Results were very similar in men and women. There was no evidence that this variant is associated with diabetes-related intermediate traits, including several measures of insulin secretion and resistance. Our results, together with those from another recent genetic study, strengthen evidence that SHBG and sex hormones are involved in the aetiology of type 2 diabetes.

Trained Volunteers With Type 2 Diabetes Experience Significant Health Benefits When Providing Peer Support.

Trained lay volunteers may have value in supporting lifestyle change programs in the prevention of type 2 diabetes, but the potential health benefits (or harms) experienced by these lay volunteers have not been well described. This is important, as this is an appealing model in terms of workforce planning. The aim of the prespecified quantitative study reported here, was to examine the possible health benefits or harms experienced by these trained lay volunteers with type 2 diabetes. In a large type 2 diabetes prevention program, we recruited and trained 104 lay volunteers with type 2 diabetes themselves, to act as diabetes prevention mentors and codeliver the lifestyle intervention. Mentors made motivational telephone calls to 461 participants randomized to one of the trial arms to encourage lifestyle changes. Weight, diet, physical activity, well-being, quality of life, diabetes-specific self-efficacy, and glycaemic control were measured at baseline, 12 and 24 months. Average mentor age was 62.0 years, 57 (54.8%) were male, 92 (88.5%) were overweight or obese (BMI>30 kg/m2). At 12 months, mentor dietary behaviors (fat and fiber intake) improved significantly, sedentary time spent fell significantly, and diabetes specific self-efficacy scores significantly increased. These significant improvements, with no evidence of harms, suggest lay volunteers with type 2 diabetes codelivering a lifestyle intervention, may themselves experience health benefits from volunteering.

Quantity and specificity of action-plans as predictors of weight loss: analysis of data from the Norfolk Diabetes Prevention Study (NDPS).

OBJECTIVE: Investigate associations between quantity, content and specificity of action-plans and weight loss in a diabetes prevention study. DESIGN: Prospective cohort study nested within a randomised controlled trial. Participants completed action-planning worksheets during intervention sessions. MAIN OUTCOME MEASURES: Action-plans were coded in terms of: number of plans set, their content, and specificity. Multivariate regression analyses assessed associations with weight loss at four-months. RESULTS: 890 planning-worksheets from 106 participants were analysed. Participants wrote a mean of 2.12 (SD = 1.20) action-plans per worksheet, using a mean of 2.20 (SD = 0.68) specificity components per action-plan. Quantity of action-plans per worksheet decreased over time (r = -0.137, p < 0.001) and increased quantity was associated with reduced specificity [r = -.215, p < 0.001]. Walking (34.9% of action-plans) and reducing high fat/sugar snacks (26.1%) were the most commonly planned lifestyle actions. In multivariate modelling, increased quantity of action-plans was associated with greater weight loss (R2 = 0.135, Unstandardised Beta = 0.144, p = 0.002). Specificity was not significantly associated with weight-loss (p = 0.096). CONCLUSION: Producing more action-plans was associated with greater weight loss. Further research should directly compare more versus less specific action-plans and explore ways to sustain engagement in action-planning. Our findings imply that participants should freely set numerous action-plans, rather than being encouraged to focus on specificity.Supplemental data for this article is available online at https://doi.org/10.1080/08870446.2022.2055026 .

Cost-effectiveness of a lifestyle intervention in preventing Type 2 diabetes.

OBJECTIVES: Previous research has suggested people with impaired fasting glucose (IFG) are less likely to develop Type 2 diabetes (T2DM) if they receive prolonged structured diet and exercise advice. This study examined the within-trial cost-effectiveness of such lifestyle interventions. METHODS: Screen-detected participants with either newly diagnosed T2DM or IFG were randomized 2:1 to intervention versus control (usual care) between February and December 2009, in Norfolk (UK). The intervention consisted of group based education, physiotherapy and peer support sessions, plus telephone contacts from T2DM volunteers. We monitored healthcare resource use, intervention costs, and quality of life (EQ-5D). The incremental cost per quality-adjusted life-year (QALY) gain (incremental cost effectiveness ratio [ICER]), and cost effectiveness acceptability curves (CEAC) were estimated. RESULTS: In total, 177 participants were recruited (118 intervention, 59 controls), with a mean follow-up of 7 months. Excluding screening and recruitment costs, the mean cost was estimated to be £551 per participant in the intervention arm, compared with £325 in the control arm. The QALY gains were -0.001 and -0.004, respectively. The intervention was estimated to have an ICER of £67,184 per QALY (16 percent probability of being cost-effective at the £20,000/QALY threshold). Cost-effectiveness estimates were more favorable for IFG participants and those with longer follow-up (≥ 4 months) (ICERs of £20,620 and £17,075 per QALY, respectively). CONCLUSIONS: Group sessions to prevent T2DM were not estimated to be within current limits of cost-effectiveness. However, there was a large degree of uncertainty surrounding these estimates, suggesting the need for further research.

Lack of association of colonic epithelium telomere length and oxidative DNA damage in Type 2 diabetes under good metabolic control.

BACKGROUND: Telomeres are DNA repeat sequences necessary for DNA replication which shorten at cell division at a rate directly related to levels of oxidative stress. Critical telomere shortening predisposes to cell senescence and to epithelial malignancies. Type 2 diabetes is characterised by increased oxidative DNA damage, telomere attrition, and an increased risk of colonic malignancy. We hypothesised that the colonic mucosa in Type 2 diabetes would be characterised by increased DNA damage and telomere shortening. METHODS: We examined telomere length (by flow fluorescent in situ hybridization) and oxidative DNA damage (flow cytometry of 8 - oxoguanosine) in the colonic mucosal cells of subjects with type 2 diabetes (n = 10; mean age 62.2 years, mean HbA1c 6.9%) and 22 matched control subjects. No colonic pathology was apparent in these subjects at routine gastrointestinal investigations. RESULTS: Mean colonic epithelial telomere length in the diabetes group was not significantly different from controls (10.6 [3.6] vs. 12.1 [3.4] Molecular Equivalent of Soluble Fluorochrome Units [MESF]; P = 0.5). Levels of oxidative DNA damage were similar in both T2DM and control groups (2.6 [0.6] vs. 2.5 [0.6] Mean Fluorescent Intensity [MFI]; P = 0.7). There was no significant relationship between oxidative DNA damage and telomere length in either group (both p > 0.1). CONCLUSION: Colonic epithelium in Type 2 diabetes does not differ significantly from control colonic epithelium in oxidative DNA damage or telomere length. There is no evidence in this study for increased oxidative DNA damage or significant telomere attrition in colonic mucosa as a carcinogenic mechanism.

Discordance in glycemic categories and regression to normality at baseline in 10,000 people in a Type 2 diabetes prevention trial.

The world diabetes population quadrupled between 1980 and 2014 to 422 million and the enormous impact of Type 2 diabetes is recognised by the recent creation of national Type 2 diabetes prevention programmes. There is uncertainty about how to correctly risk stratify people for entry into prevention programmes, how combinations of multiple 'at high risk' glycemic categories predict outcome, and how the large recently defined 'at risk' population based on an elevated glycosylated haemoglobin (HbA1c) should be managed. We identified all 141,973 people at highest risk of diabetes in our population, and screened 10,000 of these with paired fasting plasma glucose and HbA1c for randomisation into a very large Type 2 diabetes prevention trial. Baseline discordance rate between highest risk categories was 45.6%, and 21.3-37.0% of highest risk glycaemic categories regressed to normality between paired baseline measurements (median 40 days apart). Accurate risk stratification using both fasting plasma glucose and HbA1c data, the use of paired baseline data, and awareness of diagnostic imprecision at diagnostic thresholds would avoid substantial overestimation of the true risk of Type 2 diabetes and the potential benefits (or otherwise) of intervention, in high risk subjects entering prevention trials and programmes.

Metformin in non-diabetic hyperglycaemia: the GLINT feasibility RCT.

BACKGROUND: The treatment of people with diabetes with metformin can reduce cardiovascular disease (CVD) and may reduce the risk of cancer. However, it is unknown whether or not metformin can reduce the risk of these outcomes in people with elevated blood glucose levels below the threshold for diabetes [i.e. non-diabetic hyperglycaemia (NDH)]. OBJECTIVE: To assess the feasibility of the Glucose Lowering In Non-diabetic hyperglycaemia Trial (GLINT) and to estimate the key parameters to inform the design of the full trial. These parameters include the recruitment strategy, randomisation, electronic data capture, postal drug distribution, retention, study medication adherence, safety monitoring and remote collection of outcome data. DESIGN: A multicentre, individually randomised, double-blind, parallel-group, pragmatic, primary prevention trial. Participants were individually randomised on a 1 : 1 basis, blocked within each site. SETTING: General practices and clinical research facilities in Cambridgeshire, Norfolk and Leicestershire. PARTICIPANTS: Males and females aged ≥ 40 years with NDH who had a high risk of CVD. INTERVENTIONS: Prolonged-release metformin (500 mg) (Glucophage® SR, Merck KGaA, Bedfont Cross, Middlesex, UK) or the matched placebo, up to three tablets per day, distributed by post. MAIN OUTCOME MEASURES: Recruitment rates; adherence to study medication; laboratory results at baseline and 3 and 6 months; reliability and acceptability of study drug delivery; questionnaire return rates; and quality of life. RESULTS: We sent 5251 invitations, with 511 individuals consenting to participate. Of these, 249 were eligible and were randomised between March and November 2015 (125 to the metformin group and 124 to the placebo group). Participants were followed up for 0.99 years [standard deviation (SD) 0.30 years]. The use of electronic medical records to identify potentially eligible individuals in individual practices was resource intensive. Participants were generally elderly [mean age 70 years (SD 6.7 years)], overweight [mean body mass index 30.1 kg/m2 (SD 4.5 kg/m2)] and male (88%), and the mean modelled 10-year CVD risk was 28.8% (SD 8.5%). Randomisation, postal delivery of the study drug and outcome assessment using registers/medical records were feasible and acceptable to participants. Most participants were able to take three tablets per day, but premature discontinuation of the study drug was common (≈30% of participants by 6 months), although there were no differences between the groups. All randomised participants returned questionnaires at baseline and 67% of participants returned questionnaires by the end of the study. There was no between-group difference in Short Form questionnaire-8 items or EuroQol-5 Dimensions scores. Compared with placebo, metformin was associated with small improvements in the mean glycated haemoglobin level [-0.82 mmol/mol, 95% confidence interval (CI) -1.39 to -0.24 mmol/mol], mean estimated glomerular filtration rate (2.31 ml/minute/1.73 m2, 95% CI -0.2 to 4.81 ml/minute/1.73 m2) and mean low-density lipoprotein cholesterol level (-0.11 mmol/l, 95% CI -0.25 to 0.02 mmol/l) and a reduction in mean plasma vitamin B12 level (-16.4 ng/l, 95% CI -32.9 to -0.01 ng/l). There were 35 serious adverse events (13 in the placebo group, 22 in the metformin group), with none deemed to be treatment related. LIMITATIONS: Changes to sponsorship reduced the study duration, the limited availability of information in medical records reduced recruitment efficiency and discontinuation of study medication exceeded forecasts. CONCLUSIONS: A large, pragmatic trial comparing the effects of prolonged-release metformin and placebo on the risk of CVD events is potentially feasible. However, changes to the study design and conduct are recommended to enable an efficient scaling up of the trial. Recommendations include changing the inclusion criteria to recruit people with pre-existing CVD to increase the recruitment and event rates, using large primary/secondary care databases to increase recruitment rates, conducting follow-up remotely to improve efficiency and including a run-in period prior to randomisation to optimise trial adherence. TRIAL REGISTRATION: Current Controlled Trials ISRCTN34875079. FUNDING: The project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 18. See the NIHR Journals Library website for further project information. Merck KGaA provided metformin and matching placebo.

Low density lipoprotein from patients with Type 2 diabetes increases expression of monocyte matrix metalloproteinase and ADAM metalloproteinase genes.

AIMS: Type 2 diabetes is characterised by increased plasma concentrations of pro-inflammatory cytokines [such as tumour necrosis factor - alpha; TNF-alpha] and soluble forms of adhesion molecules involved in leukocyte - endothelial interactions. These molecules are synthesised as transmembrane proteins and the plasma soluble forms are generated by ectodomain cleavage from the cell surface by members of the ADAM [adisintegrin and metalloproteinase] proteinase family. We hypothesised that plasma low density lipoprotein [LDL] from subjects with Type 2 diabetes would influence in vitro monocytic ADAM and matrix metalloproteinase [MMP] gene expression differently compared to control LDL. METHODS: We examined relative mRNA expression by real time PCR in a monocytic cell line [THP-1] cultured for 4, 8 and 24 hrs with human plasma LDL derived from subjects with [n = 5] or without [n = 4] Type 2 diabetes. Gene expression for MMP-1 and 9, and ADAM - 8, 15, 17 and 28 was studied. RESULTS: Type 2 diabetes LDL significantly increased gene expression of MMP - 1 [p < 0.01] MMP - 9 [p < 0.001], and ADAM 17 [p < 0.05], - 28 [p < 0.01] and - 15 [p < 0.01] compared to control LDL. Type 2 diabetes LDL had disparate effects on inhibitors of MMP. CONCLUSION: These data suggest that Type 2 diabetes LDL could lead to increased adhesion molecule and TNF alpha cell surface shedding, and vascular plaque instability, by promoting increased expression of ADAM and MMP genes.

Pro-oxidant effect of alpha-tocopherol in patients with type 2 diabetes after an oral glucose tolerance test--a randomised controlled trial.

BACKGROUND: As a part of a larger study investigating the effects of alpha-tocopherol on gene expression in type 2 diabetics we observed a pro-oxidant effect of alpha-tocopherol which we believe may be useful in interpreting outcomes of large intervention trials of alpha-tocopherol. METHODS: 19 type 2 diabetes subjects were randomised into two groups taking either 1200 IU/day of alpha-tocopherol or a matched placebo for 4 weeks. On day 0 and 29 of this study oxidative DNA damage was assessed in mononuclear cells from fasted blood samples and following a 2 h glucose tolerance test (GTT). RESULTS: On day 0 there was no significant difference in oxidative DNA damage between the two groups or following a GTT. On day 29 there was no significant difference in oxidative DNA damage in fasted blood samples, however following a GTT there was a significant increase in oxidative DNA damage in the alpha-tocopherol treatment group. CONCLUSION: High dose supplementation with alpha-tocopherol primes mononuclear cells from patients with type 2 diabetes for a potentially damaging response to acute hyperglycaemia.

Total and excess bed occupancy by age, specialty and insulin use for nearly one million diabetes patients discharged from all English Acute Hospitals.

To investigate total diabetes bed occupancy and prolonged inpatient length of stay (LOS) in all English Acute Hospitals, we analysed hospital episode statistics (HES) discharge data for all English Acute Hospitals over 4 years for ICD10 discharge codes of E10 ('insulin-dependent diabetes') or E11 ('non-insulin dependent diabetes') by age-band (18-60, 61-75 and >75 years) and specialties. We matched these data to control discharges without these codes. There were 943,613 diabetes discharges (6,508,668 bed days) and 10,724,414 matched controls. Mean diabetes LOS increased with age for each specialty and both E10 and E11 codes, but excess diabetes LOS decreased with age. Excess diabetes LOS was <1.0 days in most groups and highest (1.2 days) in insulin-dependent surgical patients under 60 years old, where 19.7% of bed days were excess. A similar pattern was seen for 76,570 diabetes inpatients with key cardiac or surgical conditions. Excess bed occupancy due to prolonged mean LOS accounted for 325,033 bed days under general medical and surgical codes. There were 25,525 discharges with diabetic ketoacidosis (126,495 bed days) in these 4 years. Excess diabetes LOS is concentrated in younger age groups. Excess bed occupancy due to prolonged LOS in medical and surgical inpatients is three times greater than bed occupancy due to diabetic ketoacidosis. Strategies to reduce excess diabetes bed occupancy should emphasize reducing inpatient LOS in younger inpatients.

Monocyte telomere shortening and oxidative DNA damage in type 2 diabetes.

OBJECTIVE: Telomeres are DNA sequences necessary for DNA replication, which shorten at cell division at a rate related to levels of oxidative stress. Once shortened to a critical length, cells are triggered into replicative senescence. Type 2 diabetes is associated with oxidative DNA damage, and we hypothesized that telomere shortening would characterize type 2 diabetes. RESEARCH DESIGN AND METHODS: We studied 21 male type 2 diabetic subjects (mean age 61.2 years, mean HbA(1c) 7.9%) selected to limit confounding effects on telomere length and 29 matched control subjects. Telomere length was measured in peripheral venous monocyte and T-cells (naïve and memory) by fluorescent in situ hybridization and oxidative DNA damage by flow cytometry of oxidized DNA bases. Peripheral insulin resistance (homeostasis model assessment) and high-sensitivity C-reactive protein (hsCRP) were measured. RESULTS: Mean monocyte telomere length in the diabetic group was highly significantly lower than in control subjects (4.0 [1.1] vs. 5.5 [1.1]; P < 0.0001), without significant differences in lymphocyte telomere length. There was a trend toward increased oxidative DNA damage in all diabetes cell types examined and a significant inverse relationship between oxidative DNA damage and telomere length (r = -0.55; P = 0.018) in the diabetic group. Telomere length was unrelated to plasma CRP concentration or insulin resistance. CONCLUSIONS: Monocyte telomere shortening in type 2 diabetes could be due to increased oxidative DNA damage to monocyte precursors during cell division. This data suggests that monocytes adhering to vascular endothelium and entering the vessel wall in type 2 diabetes are from a population with shorter telomeres and at increased risk of replicative senescence within vascular plaque.

Monocyte matrix and ADAM metalloproteinase expression in type 2 diabetes after aspirin therapy.

The matrix metalloproteinase system (MMP and the TIMP inhibitors), and the ADAM metalloproteinases, have roles in maintaining vascular plaque stability and the shedding of cell surface molecules, such as TNF-alpha and adhesion molecules; aspirin suppresses MMP expression and ADAM activity from some cell lines in vitro. In a randomised prospective controlled study, we examined peripheral venous monocyte MMP-9, TIMP-1 and ADAM mRNA levels, and protein expression, in subjects with type 2 diabetes (n=10) and controls (n=14) before and after oral aspirin therapy (150mg daily for 14 days) or no active intervention. Baseline monocyte TIMP-1 mRNA levels were significantly lower in the diabetes group (p=0.0014), although monocyte MMP-9 mRNA, and MMP-9 and TIMP-1 protein expression after culture did not differ significantly between groups. Plasma MMP-9 (p=0.027) and TIMP-1 (p=0.016) concentrations were significantly greater, and the ratio of plasma TIMP-1:MMP-9 concentrations significantly lower, in the diabetes group (p=0.023). ADAM mRNA levels did not differ significantly between groups and oral aspirin therapy had no significant effect on any variable. Type 2 diabetes is characterised by reduced monocyte TIMP-1 mRNA levels, and a lower plasma MMP-9 to TIMP-1 protein ratio compared to controls, a pattern that would promote coronary plaque instability if reproduced within vascular plaque. Monocyte ADAM mRNA levels do not differ between group and oral aspirin has no significant effect on these variables.

Young-onset type 2 diabetes families are the major contributors to genetic loci in the Diabetes UK Warren 2 genome scan and identify putative novel loci on chromosomes 8q21, 21q22, and 22q11.

A young onset of type 2 diabetes is likely to result, in part, from greater genetic susceptibility. Young-onset families may therefore represent a group in which genes are more easily detectable by linkage. To test this hypothesis, we conducted age at diagnosis (AAD) stratified linkage analyses in the Diabetes UK Warren 2 sibpairs. In the previously published unstratified analysis, evidence for linkage (logarithm of odds [LOD] >1.18) was found at seven loci. The LOD scores at these seven loci were higher in the 245 families with AAD <55 years (L55) compared with the 328 families with AAD >55 years (G55). Five of these seven loci (1q24-25, 5q13, 8p21-22, 8q24.2, and 10q23.2) had LOD scores >1.18 in the L55 subset but only one (8p21-22) did in the G55 subset. Two additional loci (8q21.13 and 21q22.2) showed evidence for linkage in the L55 subset alone. Another locus (22q11) showed evidence for linkage in a subset of families with AAD <45 years. Using a locus-counting approach, the L55 subset had significantly more loci (P approximately 0.01) than expected under the null hypothesis of no linkage across the LOD score range 0.59-3.0. In contrast, the G55 subset contained no more susceptibility loci than that expected by chance. In conclusion, young-onset families provide both disproportionate evidence for linkage to known loci and evidence for additional novel loci. Our data confirm our hypothesis that families segregating young-onset type 2 diabetes represent a more powerful resource for defining susceptibility genes by linkage.

Association studies of insulin receptor substrate 1 gene (IRS1) variants in type 2 diabetes samples enriched for family history and early age of onset.

The gene encoding insulin receptor substrate-1 (IRS1) represents a strong biological candidate for a contributory role in type 2 diabetes susceptibility. Indeed, functional studies have implicated the G971R variant, and a recent meta-analysis of 27 association studies suggested that carriage of 971R was associated with a 25% increase in disease risk. However, this association has not been evaluated in large samples. The present study genotyped the P512A and G971R IRS1 variants in 971 U.K. type 2 diabetic subjects ascertained for strong family history and/or early onset, as well as 1,257 control subjects matched by ethnicity. There was no evidence for association with type 2 diabetes for either variant. (For example, the odds ratio [OR] for carriage of 971R was 1.11 [95% CI 0.86-1.44, P = 0.44]) An updated meta-analysis (31 studies: 5,104 case and 7,418 control subjects) remained significant for the G971R association (P = 0.025), albeit with a diminished OR (1.15 [95% CI 1.02-1.31]). Additional studies of IRS1 variation will be required to obtain a robust estimate of the overall contribution of IRS1 variation to type 2 diabetes susceptibility, but the current study suggests that previous studies have overestimated the magnitude of this effect.

Large-scale association studies of variants in genes encoding the pancreatic beta-cell KATP channel subunits Kir6.2 (KCNJ11) and SUR1 (ABCC8) confirm that the KCNJ11 E23K variant is associated with type 2 diabetes.

The genes ABCC8 and KCNJ11, which encode the subunits sulfonylurea receptor 1 (SUR1) and inwardly rectifying potassium channel (Kir6.2) of the beta-cell ATP-sensitive potassium (K(ATP)) channel, control insulin secretion. Common polymorphisms in these genes (ABCC8 exon 16-3t/c, exon 18 T/C, KCNJ11 E23K) have been variably associated with type 2 diabetes, but no large ( approximately 2,000 subjects) case-control studies have been performed. We evaluated the role of these three variants by studying 2,486 U.K. subjects: 854 with type 2 diabetes, 1,182 population control subjects, and 150 parent-offspring type 2 diabetic trios. The E23K allele was associated with diabetes in the case-control study (odds ratio [OR] 1.18 [95% CI 1.04-1.34], P = 0.01) but did not show familial association with diabetes. Neither the exon 16 nor the exon 18 ABCC8 variants were associated with diabetes (1.04 [0.91-1.18], P = 0.57; 0.93 [0.71-1.23], P = 0.63, respectively). Meta-analysis of all case-control data showed that the E23K allele was associated with type 2 diabetes (K allele OR 1.23 [1.12-1.36], P = 0.000015; KK genotype 1.65 [1.34-2.02], P = 0.000002); but the ABCC8 variants were not associated. Our results confirm that E23K increases risk of type 2 diabetes and show that large-scale association studies are important for the identification of diabetes susceptibility alleles.

Evidence from a large U.K. family collection that genes influencing age of onset of type 2 diabetes map to chromosome 12p and to the MODY3/NIDDM2 locus on 12q24.

Additional information on genetic susceptibility effects relevant to type 2 diabetes pathogenesis can be extracted from existing genome scans by extending examination to related phenotypes such as age at disease onset. In this study, we report the reanalysis of data from 573 U.K. sibships ascertained for multiplex type 2 diabetes, using age at onset (assessed by the proxy measure of age at diagnosis) as the phenotype of interest. Genome-wide evidence for linkage to age at diagnosis was evaluated using both variance components and Haseman-Elston (HECOM) regression approaches, with extensive simulations to derive empirical significance values. There was broad agreement across analyses with six regions of interest (logarithm of odds [LOD] >/==" BORDER="0">1.18) identified on chromosomes 1qter, 4p15-4q12, 5p15, 12p13-12q13, 12q24, and 14q12-14q21. The strongest empirically "suggestive" evidence for linkage comes from regions on chromosome 12. The first region (12p13-12q13), peaking at D12S310 (variance components LOD [LOD(VC)] = 2.08, empirical pointwise P = 0.0007; HECOM LOD [LOD(HECOM)] = 2.58, P = 0.0010) seems to be novel. The second (12q24) peaking between D12S324 and D12S1659 (LOD(VC) = 1.87, P = 0.0016; LOD(HECOM) = 1.93, P = 0.0027) overlaps a region showing substantial prior evidence for diabetes linkage. These data provide additional evidence that genes mapping to these chromosomal regions are involved in the susceptibility to, and/or development of, type 2 diabetes.

Monocyte matrix metalloproteinase production in Type 2 diabetes and controls--a cross sectional study.

BACKGROUND: Coronary plaque rupture may result from localised over expression of matrix metalloproteinases (MMPs) within the plaque by infiltrating monocyte-macrophages. As MMP expression can be promoted by the modified lipoproteins, oxidative stress and hyperglycaemia that characterises Type 2 diabetes, we hypothesised that peripheral monocytes in these patients, exposed to these factors in vivo, would demonstrate increased MMP production compared to controls. METHODS: We examined peripheral venous monocyte expression of MMP and tissue inhibitor of metalloproteinase-1 (TIMP-1) in 18 controls and 22 subjects with Type 2 diabetes and no previous cardiovascular complications. RESULTS: No significant difference in MMP-1, 3 or 9 or TIMP-1 production was observed between control and diabetes groups. CONCLUSIONS: Monocyte MMP-1, 3, and 9, and TIMP-1, production are not abnormal in Type 2 diabetes. This data cannot be extrapolated to monocyte-macrophage behaviour in the vessel wall, but it does suggest MMP and TIMP-1 expression prior to monocyte infiltration and transformation are not abnormal in Type 2 diabetes.

Plasma matrix metalloproteinases, low density lipoprotein oxidisability and soluble adhesion molecules after a glucose load in Type 2 diabetes.

BACKGROUND: Acute hyperglycaemia is an independent cardiovascular risk factor in Type 2 diabetes which may be mediated through increased oxidative damage to plasma low density lipoprotein, and in vitro, high glucose concentrations promote proatherogenic adhesion molecule expression and matrix metalloproteinase expression. METHODS: We examined these atherogenic risk markers in 21 subjects with Type 2 diabetes and 20 controls during an oral 75 g glucose tolerance test. Plasma soluble adhesion molecule concentrations [E-selectin, VCAM-1 and ICAM-1], plasma matrix metalloproteinases [MMP-3 and 9] and plasma LDL oxidisability were measured at 30 minute intervals. RESULTS: In the diabetes group, the concentrations of all plasma soluble adhesion molecules fell promptly [all p < 0.0001] related principally to glycaemic excursions, but such changes also occurred in the control group. Plasma MMP-3 and -9 concentrations were lower [p < 0.05], and LDL oxidisability greater [p < 0.01] in the diabetes group but did not change in either group. There was a direct relationship between plasma MMP-9 and s ICAM-1 in the controls [r = 0.62; p = 0.006] perhaps suggesting a functional relationship between s ICAM-1 shedding and MMP-9. CONCLUSIONS: A glucose load leads to a rapid fall in plasma soluble adhesion molecule concentrations in Type 2 diabetes and controls, perhaps reflecting reduced generation of soluble from membrane forms during enhanced leukocyte-endothelial adhesion or increased hepatic clearance, without changes in plasma matrix metalloproteinase concentrations or low density lipoprotein oxidisability. These in vivo findings are in contrast with in vitro data.