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Diabetes mellitus is a common long-term childhood condition, which paediatricians, allied healthcare professionals and paediatric trainees will encounter frequently. General or acute paediatric trainees will be involved in treatment initiation, requesting appropriate investigations and continued management. The vast majority of children with diabetes have type 1 diabetes mellitus (T1DM) and the minority have type 2 diabetes mellitus (T2DM) or monogenic causes (also known as maturity-onset diabetes of the young). Individuals with T1DM tend to present more acutely and may be unwell with diabetic ketoacidosis. Those with T2DM and MODY usually present less acutely. However, there is considerable overlap in the clinical features, which may lead to diagnostic uncertainty. It is essential to clarify the subtype of diabetes mellitus as this allows tailored management including education, lifestyle modifications, medication and appropriate family counselling. In this review, we consider three adolescents presenting with symptoms and signs of diabetes, highlight the key features of different types of MODY and consider their differential diagnoses. [ABSTRACT FROM AUTHOR]

Objective and context: Maturity onset diabetes of the young due to variants in HNF1A (HNF1A‐MODY) is the most common form of monogenic diabetes. Individuals with HNF1A‐MODY usually have a lean phenotype which contrasts with type 2 diabetes (T2DM). Data from hepatocytes derived from Hnf1a knock‐out mice demonstrated dysregulation of 11β‐hydroxysteroid dehydrogenase type 1 (11β‐HSD1), which regulates glucocorticoid availability and action in target tissues, together with 11β‐HSD2 and steroid A‐ring reductases, 5α‐ and 5β‐reductase. We proposed that altered glucocorticoid metabolism might underpin some of the phenotypic differences between patients with HNF1A‐MODY and those with T2DM. Design: A retrospective matched cohort study. Patients and measurements: 24‐hours urine steroid metabolome profiling was carried out by gas chromatography‐mass spectrometry in 35 subjects with HNF1A‐MODY, 35 individuals with T2DM and 35 healthy controls matched for age, sex and BMI. The steroid metabolites were expressed as μg/L in all groups and measured in mid‐morning urine in diabetic subjects and 24‐hour urine collection in healthy controls. Hence, only ratios were compared not the individual steroids. Established ratios of glucocorticoid metabolites were used to estimate 11β‐HSD1/2 and 5α‐ and 5β‐reductase activities. Results: While 11β‐HSD1 activity was similar in all groups, 11β‐HSD2 activity was significantly lower in subjects with HNF1A‐MODY and T2DM than in healthy controls. The ratio of 5β‐ to 5α‐metabolites of cortisol was higher in subjects with HNF1A‐MODY than in T2DM and healthy controls, probably due to increased activity of the 5β‐reductase (AKR1D1) in HNF1A‐MODY. Conclusions: This is the first report of steroid metabolites in HNF1A‐MODY. We have identified distinct differences in steroid metabolism pathways in subjects with HNF1A‐MODY that have the potential to alter steroid hormone availability. Further studies are required to explore whether these changes link to phenotype. [ABSTRACT FROM AUTHOR]

To investigate the genetic basis of type 2 diabetes (T2D) to high resolution, the GoT2D and T2D-GENES consortia catalogued variation from whole-genome sequencing of 2,657 European individuals and exome sequencing of 12,940 individuals of multiple ancestries. Over 27M SNPs, indels, and structural variants were identified, including 99% of low-frequency (minor allele frequency [MAF] 0.1–5%) non-coding variants in the whole-genome sequenced individuals and 99.7% of low-frequency coding variants in the whole-exome sequenced individuals. Each variant was tested for association with T2D in the sequenced individuals, and, to increase power, most were tested in larger numbers of individuals (>80% of low-frequency coding variants in ~82 K Europeans via the exome chip, and ~90% of low-frequency non-coding variants in ~44 K Europeans via genotype imputation). The variants, genotypes, and association statistics from these analyses provide the largest reference to date of human genetic information relevant to T2D, for use in activities such as T2D-focused genotype imputation, functional characterization of variants or genes, and other novel analyses to detect associations between sequence variation and T2D.

OBJECTIVE - Misdiagnosis of maturity-onset diabetes of the young (MODY) remains widespread, despite the benefits of optimized management. This cross-sectional study examined diagnostic misclassification of MODY in subjects with clinically labeled young adult-onset type 1 and type 2 diabetes by extending genetic testing beyond current guidelines. RESEARCH DESIGN AND METHODS - Individuals were selected for diagnostic sequencing if they displayed features atypical for their diagnostic label. From 247 case subjects with clinically labeled type 1 diabetes, we sequenced hepatocyte nuclear factor 1 α (HNF1A)and hepatocyte nuclear factor 4 α (HNF4A) in 20 with residual β - cell function ≥3 years from diagnosis (random or glucagon-stimulated C-peptide ≥0.2 nmol/L). From 322 with clinically labeled type 2 diabetes, we sequenced HNF1A and HNF4A in 80 with diabetes diagnosed ≤30 years and/or diabetes diagnosed ≤45 years without metabolic syndrome.We also sequenced the glucokinase (GCK) in 40 subjects with mild fasting hyperglycemia. RESULTS - In the type 1 diabetic group, two HNF1A mutations were found (0.8% prevalence). In type 2 diabetic subjects, 10 HNF1A,two HNF4A, and one GCK mutation were identified (4.0%). Only 47% of MODY case subjects identified met current guidelines for diagnostic sequencing. Follow-up revealed a further 12 mutation carriers among relatives. Twenty-seven percent of newly identified MODY subjects changed treatment, all with improved glycemic control (HbA1c 8.8vs.7.3% at 3months; P = 0.02). CONCLUSIONS - The systematic use of widened diagnostic testing criteria doubled the numbers of MODY case subjects identified compared with current clinical practice. The yield was greatest in young adult-onset type 2 diabetes. We recommend that all patients diagnosed before age 30 and with presence of C-peptide at 3 year's duration are considered for molecular diagnostic analysis. [ABSTRACT FROM AUTHOR]

Background: There is considerable interest in the hypothesis that low frequency, intermediate penetrance variants contribute to the proportion of Type 2 Diabetes (T2D) susceptibility not attributable to the common variants uncovered through genome-wide association approaches. Genes previously implicated in monogenic and multifactorial forms of diabetes are obvious candidates in this respect. In this study, we focussed on exons 8-10 of the HNF1A gene since rare, penetrant mutations in these exons (which are only transcribed in selected HNF1A isoforms) are associated with a later age of diagnosis of Maturity onset diabetes of the young (MODY) than mutations in exons 1-7. The age of diagnosis in the subgroup of HNF1A-MODY individuals with exon 8-10 mutations overlaps with that of early multifactorial T2D, and we set out to test the hypothesis that these exons might also harbour low-frequency coding variants of intermediate penetrance that contribute to risk of multifactorial T2D. Methodology and Principal Findings: We performed targeted capillary resequencing of HNF1A exons 8-10 in 591 European T2D subjects enriched for genetic aetiology on the basis of an early age of diagnosis (≥45 years) and/or family history of T2D (≤1 affected sibling). PCR products were sequenced and compared to the published HNF1A sequence. We identified several variants (rs735396 [IVS9-24T>C], rs1169304 [IVS8+29T>C], c.1768+44C>T [IVS9+44C>T] and rs61953349 [c.1545G.A, p.T515T] but no novel non-synonymous coding variants were detected. Conclusions and Significance: We conclude that low frequency, nonsynonymous coding variants in the terminal exons of HNF1A are unlikely to contribute to T2D-susceptibility in European samples. Nevertheless, the rationale for seeking lowfrequency causal variants in genes known to contain rare, penetrant mutations remains strong and should motivate efforts to screen other genes in a similar fashion. [ABSTRACT FROM AUTHOR]

Mutations in the LMNA gene (encoding lamin A/C) underlie familial partial lipodystrophy, a syndrome of monogenic insulin resistance and diabetes. LMNA maps to the well-replicated diabetes-linkage region on chromosome 1q, and there are reported associations between LMNA single nucleotide polymorphisms (SNPs) (particularly rs4641; H566H) and metabolic syndrome components. We examined the relationship between LMNA variation and type 2 diabetes (using six tag SNPs capturing >90% of common variation) in several large datasets. Analysis of 2,490 U.K. diabetic case and 2,556 control subjects revealed no significant associations at either genotype or haplotype level: the minor allele at rs4641 was no more frequent in case subjects (allelic odds ratio [OR] 1.07 [95% CI 0.98-1.17], P = 0.15). In 390 U.K. trios, family-based association analyses revealed nominally significant overtransmission of the major allele at rs12063564 (P = 0.01), which was not corroborated in other samples. Finally, genotypes for 2,817 additional subjects from the International 1q Consortium revealed no consistent case-control or family-based associations with LMNA variants. Across all our data, the OR for the rs4641 minor allele approached but did not attain significance (1.07 [0.99-1.15], P = 0.08). Our data do not therefore support a major effect of LMNA variation on diabetes risk. However, in a meta-analysis including other available data, there is evidence that rs4641 has a modest effect on diabetes susceptibility (1.10 [1.04-1.16], P = 0.001). Diabetes 56:879-883, 2007 [ABSTRACT FROM AUTHOR]

A limited number of studies have assessed the risk of common diseases when combining information from several predisposing polymorphisms. In most cases, individual polymorphisms only moderately increase risk (∼20%), and they are thought to be unhelpful in assessing individuals' risk clinically. The value of analyzing multiple alleles simultaneously is not well studied. This is often because, for any given disease, very few common risk alleles have been confirmed. Methods and Findings Three common variants (Lys23 of KCNJ11, Pro12 of PPARG, and the T allele at rs7903146 of TCF7L2) have been shown to predispose to type 2 diabetes mellitus across many large studies. Risk allele frequencies ranged from 0.30 to 0.88 in controls. To assess the combined effect of multiple susceptibility alleles, we genotyped these variants in a large case-control study (3,668 controls versus 2,409 cases). Individual allele odds ratios (ORs) ranged from 1.14 (95% confidence interval [CI], 1.05 to 1.23) to 1.48 (95% CI, 1.36 to 1.60). We found no evidence of gene-gene interaction, and the risks of multiple alleles were consistent with a multiplicative model. Each additional risk allele increased the odds of type 2 diabetes by 1.28 (95% CI, 1.21 to 1.35) times. Participants with all six risk alleles had an OR of 5.71 (95% CI, 1.15 to 28.3) compared to those with no risk alleles. The 8.1% of participants that were double-homozygous for the risk alleles at TCF7L2 and Pro12Ala had an OR of 3.16 (95% CI, 2.22 to 4.50), compared to 4.3% with no TCF7L2 risk alleles and either no or one Glu23Lys or Pro12Ala risk alleles. Conclusions Combining information from several known common risk polymorphisms allows the identification of population subgroups with markedly differing risks of developing type 2 diabetes compared to those obtained using single polymorphisms. This approach may have a role in future preventative measures for common, polygenic diseases. [ABSTRACT FROM AUTHOR]

Recent evidence supports the strong overlap between genes implicated in monogenic diabetes and susceptibility to type 2 diabetes. Transient neonatal diabetes mellitus (TNDM) is a rare disorder associated with overexpression of genes at a paternally expressed imprinted locus on chromosome 6q24. There are two overlapping genes in this region: the transcription factor zinc finger protein associated with cell cycle control and apoptosis (ZAC also known as PLAGL1) and HYMA1, which encodes an untranslated mRNA. Several type 2 diabetes linkage studies have reported linkage to chromosome 6q22-25. We hypothesized that common genetic variation at this TNDM region influences type 2 diabetes susceptibility. In addition to the coding regions, we used comparative genomic analysis to identify conserved noncoding regions, which were resequenced for single nucleotide polymorphism (SNP) discovery in 47 individuals. Twenty-six SNPs were identified. Fifteen tag SNPs (tSNPs) were successfully genotyped in a large case-control (n = 3,594) and family-based (n = 1,654) study. We did not find any evidence of association or overtransmission of any tSNP to affected offspring or of a parent-of-origin effect. Using a study sufficiently powered to detect odds ratios of <1.2, we conclude that common variation in the TNDM region does not play an important role in the genetic susceptibility to type 2 diabetes. Diabetes 55:2272-2276, 2006 [ABSTRACT FROM AUTHOR]

HNF1α (TCF1) is a key transcription factor that is essential for pancreatic β-cell development and function. Rare mutations of HNF1α cause maturity-onset diabetes of the young. A common variant, G319S, private to the Oji-Cree population, predisposes to type 2 diabetes, but the role of common HNF1α variation in European populations has not been comprehensively assessed. We determined the linkage disequilibrium and haplotype structure across the HNF1α gene region using 29 single nucleotide polymorphisms (SNPs). Eight tagging SNPs (tSNPs) that efficiently capture common haplotypes and the amino acid-changing variant, A98V, were genotyped in 5,307 subjects (2,010 type 2 diabetic case subjects, 1,643 control subjects, and 1,654 members of 521 families). We did not find any evidence of association between the tSNPs or haplotypes and type 2 diabetes. We could exclude odds ratios (ORs) > 1.25 for all tSNPs. The rare V98 allele (∼3% frequency) showed possible evidence of association with type 2 diabetes (OR 1.23 [95% CI 0.99-1.54], P = 0.07), a result that was supported by meta-analysis of this and published studies (OR 1.31 [1.08-1.59], P = 0.007). Further studies are required to investigate this association, demonstrating the difficulty of defining the role of rare (<5%) alleles in type 2 diabetes risk. Diabetes 54:2487-2491, 2005 [ABSTRACT FROM AUTHOR]

OBJECTIVE — Young adults with newly diagnosed apparent type 2 diabetes present the clinician with a wide differential diagnosis of possible etiology, including autoimmune and genetic causes as well as young-onset type 2 diabetes (YT2D). The characteristics of these groups have been described, but it is not known in which subjects investigation for etiology may be beneficial. RESEARCH DESIGN AND METHODS — A total of 268 unselected U.K. Caucasian subjects diagnosed at ages 18-45 years and not treated with permanent insulin for ≤6 months were studied. All subjects underwent clinical assessment and screening for GAD antibodies (GADA) and tyrosine phosphatase IA-2 antibodies (IA-2A). Screening for a common mutation in the hepatocyte nuclear factor-1α (HNF-1α) gene and the common mitochondrial mutation was performed in the antibody-negative subjects. Subjects without insulin resistance were selected for sequencing of the HNF-1α gene. RESULTS — A specific etiology was defined in 11.6% of the 268 subjects and in 24.7% of the lean subjects. Twenty-six subjects (9.7%) were positive for a β-cell antibody, one subject had familial partial lipodystrophy and the lamin A/C mutation R482W, and two subjects had the mitochondrial mutation A3243G. Two of 15 selected subjects had HNF-1α mutations, the novel missense mutation A501T, and the previously reported R583Q. CONCLUSIONS — This unselected series shows that there is considerable heterogeneity in apparent YT2D. β-Cell autoantibodies should be performed in all those presenting at ages 18-45 years. Genetic investigations can be targeted to phenotypically defined subjects. The finding of a specific etiology will allow individualization of management and give patients valuable information about their condition. [ABSTRACT FROM AUTHOR]

The orphan receptor small heterodimer partner (SHP, NR0B2) modulates the transcription activity of the MODY1 gene HNF4a. Mutations in SHP were found in 7% of Japanese obese young-onset type 2 diabetic patients and were associated with moderate obesity and increased birth weight. We investigated SHP in 1927 U.K. subjects, examining relationships with type 2 diabetes, obesity, and birth weight. Sequencing of the coding region of SHP in 122 obese, young-onset type 2 diabetic patients detected the polymorphism G171A. The polymorphism was not associated with diabetes in case control or familial association studies. The A allele (frequency 0.07) was not associated with obesity in type 2 diabetic subjects (n = 348), their parents (n = 272), or young nondiabetic adults (n = 925). However, the rare (<1%) AA homozygotes had a raised BMI in each cohort; this was significant when all cohorts were combined (Z score = 0.67 AA vs. -0.05 G/x, P = 0.02). There was no association with corrected birth weight in 382 normal babies, but the only AA baby was 4,069 g. Our study suggests that genetic variation in SHP is unlikely to be common in the predisposition to diabetes, obesity, or increased birth weight in U.K. Caucasians. [ABSTRACT FROM AUTHOR]

Abstract: Diabetes mellitus is not a single disorder but rather a heterogeneous group of diseases that differ in respect to pathogenesis, the clinical picture and the response to dietary and pharmacological treatments. Thus, the differential diagnosis of various types and forms of diabetes is of great practical importance. This is particularly true for monogenic disease forms where some spectacular applications of pharmacogenetics have recently been described. Unfortunately, most patients with monogenic diabetes such as maturity-onset diabetes of the young (MODY) or neonatal diabetes have not undergone diagnostic molecular testing, so they can not benefit from the progress seen in this field. The reasons for this include the complexity and cost of molecular diagnostics. One of ways to change this situation is to find an efficient and cheap test to screen thousands of patients for specific forms of monogenic diabetes. These tests can be based on biomarkers discovered by one of two general strategies: a candidate approach or a systematic search based on metabonomics or proteonomics. This review summarizes recent advances in the search for putative biomarkers and the perspectives of the future progress. [Copyright &y& Elsevier]

The lipodystrophies are a heterogeneous group of disorders of adipose tissue associated with insulin resistance. The sporadic form of partial lipodystrophy, characterised by fat loss from the face and upper body, is associated with complement abnormalities and mesangiocapillary glomerulonephritis type 2 (MCGN II) and the conditions are thought to have a shared autoimmune aetiology. We present the first case of the rare familial form of partial lipodystrophy, caused by a mutation in the LMNA gene, associated with MCGN II. This suggests that partial lipodystrophy of both the sporadic and familial subtypes may predispose to this condition and that the observed renal and complement abnormalities may be secondary to other factors associated with lipodystrophy. Copyright © 2004 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

The genetic causes of type 2 diabetes are not well understood. The disease has been linked to chromosome 20q12–q13.1 a region which harbors the transcription factor HNF4α. Mutations in the coding region of HNF4α cause maturity onset diabetes of the young, an autosomal dominant form of diabetes, but do not account for the linkage to this region. An enhancer element has recently been characterized 6 kb 5′ of the HNF4α P1 promoter containing binding sites for the transcription factors HNF1, HNF4, HNF3, and C/EBP, which are overlapped by glucocorticoid consensus sites. We hypothesized that variation in the enhancer element disrupts HNF4α expression in the liver and increases susceptibility to type 2 diabetes. We screened for variants of the enhancer element in 39 white UK young onset diabetic subjects, giving >95% power to identify variants with minor allele frequencies of >5%. No variants of the enhancer element were found in this population. We conclude that variation in the HNF4α enhancer element is not a common cause of susceptibility to type 2 diabetes. [Copyright &y& Elsevier]

There are limited data regarding intermittently scanned continuous glucose monitoring (isCGM) in pregnancy for women with Type 2 diabetes. We have tested the acceptability and feasibility of an isCGM method using Libre device.In a hospital-based service improvement project, 23 pregnant women (March 2022-April 2023), with Type 2 diabetes got isCGM for monitoring from 20 weeks until delivery. Women completed a structured and validated questionnaire assessing satisfaction, equipment issue, relationship with diabetes team. Two-thirds of the women were satisfied with the convenience and found it reliable. 86% wanted to use it for future pregnancies, and 90% would recommend it to others. Sensor falls off was seen in three obese women and about a tenth felt the reliability was poor in extreme ranges of sugar levels. The relationship with the diabetes team was rated high.isCGM could be a useful and well-received tool for improving glycaemic control in pregnancies with Type 2 diabetes. [ABSTRACT FROM AUTHOR]

Aims: We previously demonstrated that antennary fucosylated N-glycans on plasma proteins are regulated by HNF1A and can identify cases of Maturity-Onset Diabetes of the Young caused by HNF1A variants (HNF1A-MODY). Based on literature data, we further postulated that N-glycans with best diagnostic value mostly originate from alpha-1-acid glycoprotein (AGP). In this study we analyzed fucosylation of AGP in subjects with HNF1A-MODY and other types of diabetes aiming to evaluate its diagnostic potential.Methods: A recently developed LC-MS method for AGP N-glycopeptide analysis was utilized in two independent cohorts: a) 466 subjects with different diabetes subtypes to test the fucosylation differences, b) 98 selected individuals to test the discriminative potential for pathogenic HNF1A variants.Results: Our results showed significant reduction in AGP fucosylation associated to HNF1A-MODY when compared to other diabetes subtypes. Additionally, ROC curve analysis confirmed significant discriminatory potential of individual fucosylated AGP glycopeptides, where the best performing glycopeptide had an AUC of 0.94 (95% CI 0.90-0.99).Conclusions: A glycopeptide based diagnostic tool would be beneficial for patient stratification by providing information about the functionality of HNF1A. It could assist the interpretation of DNA sequencing results and be a useful addition to the differential diagnostic process. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: The young-onset diabetes seen in HNF1A-MODY is often misdiagnosed as Type 2 diabetes. Type 2 diabetes, unlike HNF1A-MODY, is associated with insulin resistance and a characteristic dyslipidaemia. We aimed to compare the lipid profiles in HNF1A-MODY, Type 2 diabetes and control subjects and to determine if lipids can be used to aid the differential diagnosis of diabetes sub-type. Methods: [1)] 14 subjects in each group (HNF1A-MODY, Type 2 diabetes and controls) were matched for gender and BMI. Fasting lipid profiles and HDL lipid constituents were compared in the 3 groups. [2)] HDL-cholesterol was assessed in a further 267 patients with HNF1A-MODY and 297 patients with a diagnosis of Type 2 diabetes to determine its discriminative value. Results: [1)] In HNF1A-MODY subjects, plasma-triglycerides were lower (1.36 vs. 1.93mmol/l, p=0.07) and plasma-HDL-cholesterol was higher than in subjects with Type 2 diabetes (1.47 vs. 1.15mmol/l, p=0.0008), but was similar to controls. Furthermore, in the isolated HDL; HDL-phospholipid and HDL-cholesterol ester content were higher in HNF1A-MODY, than in Type 2 diabetes (1.59 vs. 1.33mmol/L, p=0.04 and 1.10 vs. 0.83mmol/L, p=0.019, respectively), but were similar to controls (1.59 vs. 1.45mmol/L, p=0.35 and 1.10 vs. 1.21mmol/L, p=0.19, respectively). [2)] A plasma-HDL-cholesterol >1.12mmol/L was 75% sensitive and 64% specific (ROC AUC=0.76) at discriminating HNF1A-MODY from Type 2 diabetes. Conclusion: The plasma-lipid profiles of HNF1A-MODY and the lipid constituents of HDL are similar to non-diabetic controls. However, HDL-cholesterol was higher in HNF1A-MODY than in Type 2 diabetes and could be used as a biomarker to aid in the identification of patients with HNF1A-MODY. [Copyright &y& Elsevier]