Glucokinase Maturity-onset Diabetes Of The Young Research Articles

Hypoglycemic Response to Dorzagliatin in a Patient With GCK-MODY.

Metformin, insulin, and insulin secretagogues do not alter HbA1c levels in glucokinase-maturity-onset diabetes of the young (GCK-MODY). However, the efficacy of the new hypoglycemic drugs on GCK-MODY remains unclear. We describe a case of GCK-MODY with unchanged blood glucose under different therapies during an 8 years' follow-up. His HbA1c and biochemical indices under different hypoglycemic treatments were recorded. Oral antidiabetic drugs, including thiazolidinediones, dipeptidyl peptidase IV inhibitor, α-glucosidase inhibitor, and sodium-glucose cotransporter 2 inhibitor that had not been evaluated previously, did not improve the HbA1c level in this patient. However, the glucokinase activator dorzagliatin effectively and safely lowered his HbA1c level. Dorzagliatin was effective and safe in this patient with GCK-MODY, providing potential application prospects for precise treatment of GCK-MODY with dorzagliatin.

Management of monogenic diabetes in pregnancy: A narrative review.

Pregnancy in women with monogenic diabetes is potentially complex, with significant implications for both maternal and fetal health. Among these, maturity-onset diabetes of the young (MODY) stands out as a prevalent monogenic diabetes subtype frequently encountered in clinical practice. Each subtype of MODY requires a distinct approach tailored to the pregnancy, diverging from management strategies in non-pregnant individuals. Glucokinase MODY (GCK-MODY) typically does not require treatment outside of pregnancy, but special considerations arise when a woman with GCK-MODY becomes pregnant. The glycemic targets in GCK-MODY pregnancies are not exclusively dictated by the maternal/paternal MODY genotype but are also influenced by the genotype of the developing fetus. During pregnancy, the choice between sulfonylurea or insulin for treating hepatocyte nuclear factor 1-alpha (HNF1A)-MODY and HNF4A-MODY depends on the mother's specific circumstances and the available expertise. Management of other rarer MODY subtypes is individualized, with decisions made on a case-by-case basis. Therefore, a collaborative approach involving expert diabetes and obstetric teams is crucial for the comprehensive management of MODY pregnancies.

Integration of proteomics and metabolomics reveals energy and metabolic alterations induced by glucokinase (GCK) partial inactivation in hepatocytes

AimsGlucokinase (GCK) acts as the glucose sensor in maintaining glucose homeostasis. The inactivating mutation of the GCK gene leads to glucokinase-maturity onset diabetes of the young (GCK-MODY). This study aims to gain further insights into the molecular alterations triggered by GCK partial inactivation in hepatocytes, potentially underlying the favorable prognosis of GCK-MODY. Main methodsA GCK knockdown HepG2 cell model was established, and the integration of proteomics and metabolomics was used to gain a comprehensive understanding of the molecular pathway changes caused by GCK inactivation in the liver. Key findingsProteomic analysis identified 257 differential proteins. KEGG pathway enrichment analysis showed that protein expression changes in the GCK knockdown group were significantly enriched in central carbon metabolism, the TCA cycle, amino acid metabolism and the oxidative phosphorylation pathway. Among them, enzymes in the TCA cycle (PC, IDH2, SDH) were significantly downregulated in GCK-knockdown group. Targeted metabolomics revealed that in the GCK knockdown hepatocytes, TCA cycle intermediates were significantly decreased, including pyruvate, oxaloacetate, citrate and succinic acid, and three metabolites increased including glycine, betaine and homocysteine. These metabolic alterations in turn reduced the accumulation of reactive oxygen species in GCK knockdown hepatocytes. Correlation analysis indicated that TCA cycle metabolites were positively correlated with proteins involved in the TCA cycle, carbon metabolism, glycolysis, Ras signaling, fibrosis and inflammation. SignificanceIn conclusion, GCK knockdown reduced TCA cycle flux and oxidative stress in hepatocytes by influencing the levels of key transcription factors and enzymes, providing a comprehensive understanding of the effects of GCK partial inactivation on liver metabolism and molecular mechanisms.

Insights from basic adjunctive examinations of GCK-MODY, HNF1A-MODY, and type 2 diabetes: A systemic review and meta-analysis.

Glucokinase maturity-onset diabetes of the young (GCK-MODY) is difficult to distinguish from other diabetic forms. This article aims to characterize the differences in results from routine examinations between GCK-MODY and hepatocyte nuclear factor 1-α (HNF1A)-MODY or type 2 diabetes (T2D) patients in different periods of diabetes. Ovid Medline, Embase, and the Cochrane Library were searched up until October 9, 2022 for articles containing baseline characteristics of GCK-MODY, HNF1A-MOFY, and T2D, excluding pregnant women. The pooled standardized mean differences were derived using a random-effects model. Compared to HNF1A-MODY, GCK-MODY patients had lower indicators of glucose metabolism. Total triglycerides (TG) (-0.93 [-1.66, -0.21] mmol/l) were consistently lower in GCK-MODY patients in the all-family-members subgroup analysis. Compared to T2D, GCK-MODY patients were younger at diagnosis and had lower body mass index (BMI), lower high-sensitivity C-reactive protein (hsCRP) (-0.60 [-0.75, -0.44] mg/l), lower fasting C-peptide (FCP), and lower 2-hour postprandial glucose (2-h PG). Indicators of glycated hemoglobin (HbA1c) and fasting blood glucose (FPG) were consistently lower in subgroup studies with all family members of GCK-MODY patients as well. Lower HbA1c, FPG, 2-h PG, and change in 2-h PG may help to diagnose GCK-MODY differentially from HNF1A-MODY at an early stage, and lower TG may strengthen such a diagnosis in the follow-up stages. Younger age combined with lower BMI, FCP, hsCRP, and 2-h PG may be useful to distinguish GCK-MODY from MODY-like T2D, whereas results of glucose metabolism indicators such as HbA1c and FPG may not help physicians until after a long follow-up period.

Maternal and Infant Outcomes in GCK-MODY Complicated by Pregnancy.

Challenges exist in the management of Glucokinase-maturity-onset diabetes of the young (GCK-MODY), especially during pregnancy. This work aimed to evaluate the prevalence of congenital anomaly in newborns from GCK-MODY mothers, and the relationship between fetus genotype and the risk of congenital malformation as well as other adverse pregnancy outcomes. Electronic databases including PubMed, EMBASE, and Cochrane database last updated July 16, 2022, were searched. We included observational studies conducted in GCK-MODY complicated by pregnancy, and reporting at least one pregnancy outcome. We extracted data in duplicate, and the risk of bias was evaluated by the Newcastle-Ottawa Quality Assessment Scale (NOS). All statistical analysis was performed by Cochrane Review Manager. Eight studies were selected in the meta-analysis. Five were of high quality and 3 were of medium quality evaluated by NOS. A total of 257 GCK-MODY mothers and 499 offspring were enrolled. Among them, 370 offspring were divided into 2 groups: GCK-affected offspring (GCK+, n = 238) and GCK-unaffected offspring (GCK-, n = 132). The percentage of congenital malformations in GCK pregnant women's offspring was 2.4%. The risk of congenital malformations was similar between the GCK+ and GCK- group (odds ratio = 0.56; 95% CI, 0.07-4.51; I2 = 0%; P = .59). The risk of macrosomia/large for gestational age, neonatal hypoglycemia, and combined adverse neonatal outcome was significantly lower in offspring with the GCK mutation compared with non-GCK mutation carriers. The percentage of congenital malformations was 2.4% in GCK-MODY pregnant women's offspring, and newborns with the GCK mutation have lower birth complication than non-GCK mutation carriers.

Glucokinase Inactivation Ameliorates Lipid Accumulation and Exerts Favorable Effects on Lipid Metabolism in Hepatocytes

Glucokinase-maturity onset diabetes of the young (GCK-MODY) is a kind of rare diabetes with low incidence of vascular complications caused by GCK gene inactivation. This study aimed to investigate the effects of GCK inactivation on hepatic lipid metabolism and inflammation, providing evidence for the cardioprotective mechanism in GCK-MODY. We enrolled GCK-MODY, type 1 and 2 diabetes patients to analyze their lipid profiles, and found that GCK-MODY individuals exhibited cardioprotective lipid profile with lower triacylglycerol and elevated HDL-c. To further explore the effects of GCK inactivation on hepatic lipid metabolism, GCK knockdown HepG2 and AML-12 cell models were established, and in vitro studies showed that GCK knockdown alleviated lipid accumulation and decreased the expression of inflammation-related genes under fatty acid treatment. Lipidomic analysis indicated that the partial inhibition of GCK altered the levels of several lipid species with decreased saturated fatty acids and glycerolipids including triacylglycerol and diacylglycerol, and increased phosphatidylcholine in HepG2 cells. The hepatic lipid metabolism altered by GCK inactivation was regulated by the enzymes involved in de novo lipogenesis, lipolysis, fatty acid β-oxidation and the Kennedy pathway. Finally, we concluded that partial inactivation of GCK exhibited beneficial effects in hepatic lipid metabolism and inflammation, which potentially underlies the protective lipid profile and low cardiovascular risks in GCK-MODY patients.

Distinguishing the lipid profile of GCK-MODY patients and its correlation with hsCRP levels.

Glucokinase-maturity-onset diabetes of the young (GCK-MODY) is the most common monogenic diabetes in China. We have previously reported on the low levels of high-sensitivity C-reactive protein (hsCRP) in patients with GCK-MODY. In this study, we further explored the correlation between the serum lipid profiles and hsCRP levels of patients with different types of diabetes. We also proposed to determine the possible mechanism of macrovascular protection in GCK genetic variants. The serum lipid profiles of the GCK-MODY group (n=50) were compared with those of the hepatocyte nuclear factor-1 alpha (HNF1A)-MODY group (n=19), the type 1 diabetes (T1D) group (n=50), and the type 2 diabetes (T2D) group (n=54). The associations between the lipid compositions and the hsCRP levels in each group were also explored. Elevated levels of high-density lipoprotein cholesterol (HDL-C) were found in the GCK-MODY group (1.5±0.27) compared with the T1D (1.2±0.47, p<0.01) and T2D (1.3±0.3, p<0.01) groups. On the other hand, a significantly lower LDL-C level (2.4±0.69) in the GCK-MODY group compared with the T1D (2.7±0.72, p<0.01) and T2D (2.9±0.68, p<0.01) groups was also noted. A lower ratio of triglyceride to HDL-C (TG/HDL) and a lower hsCRP level were also found in the GCK-MODY group [TG/HDL=0.38 (0.25-0.52), hsCRP=0.2mg/L (0.16-0.37)] compared with the T1D group [(TG/HDL=0.56 (0.39-1.29), hsCRP=0.56mg/L (0.39-1.29), p<0.01] and the T2D group [(TG/HDL=1.6 (1.1-2.68), hsCRP=1.11mg/L (0.66-2.34), p<0.01]. Although patients with HNF1A-MODY showed similar hsCRP levels [0.17 (0.08-0.52), p>0.05] compared with the patients in the GCK-MODY group, they had higher TG levels [1.01 (0.66-1.76), p<0.05] and TG/HDL ratios [0.84 (0.56-1.31), p<0.05]. Analysis of the correlations between the hsCRP levels and lipid profiles of each group confirmed that the LnhsCRP (natural logarithm-transformed hsCRP level) was positively correlated with the LnTG (natural logarithm-transformed TG) (r=0.352, p=0.011) and the Ln(TG/HDL) ratio (r=0.283, p=0.047) only in individuals with GCK-MODY. Individuals harboring GCK variants have the characteristics of protective lipid profiles manifested as a higher level of HDL-C and a lower level of LDL-C compared with type 1 and 2 diabetes milletus (T1DM and T2DM, respectively) patients. In addition, lower ratios of TG/HDL were found to be associated with the inhibition of secretion of hsCRP, even when adjusted for the HbA1c levels in patients with GCK-MODY. It is suggested that the protective effect of macrovascular complications in GCK-MODY patients might partly be due to their unique lipid profiles associated with the suppression of inflammation.

261-OR: Dorzagliatin, a Dual-Acting Glucokinase Activator. Improves Insulin Secretion and Glucose Sensitivity in Glucokinase-Maturity-Onset Diabetes of the Young (GCK-MODY)

Glucokinase maturity onset diabetes of the young (GCK-MODY) is caused by heterozygous inactivating mutations in GCK that is not responsive to conventional glucose lowering drugs. We investigated the effects of dorzagliatin, a novel allosteric activator of hepatic and beta-cell GCK on insulin secretion rates (ISR) and glucose sensitivity (GS) in GCK-MODY and recent onset type 2 diabetes (T2D) . In a double-blind, randomized cross-over study, 8 GCK-MODY (mean±SD age 36.1­±6.4years) and T2D subjects (mean age 50.2±6.9 years, median T2D duration 0.90 [0.60-1.42] years) underwent 2-hour 12 mmol/L hyperglycemic clamps following a single oral dose of dorzagliatin 75mg or matched placebo. Insulin and C-peptide were measured. GCK-MODY group showed significantly higher absolute (mean±SD 432±85 versus 272±91 pmol/min/m2, p=0.002) and incremental (342­±91 vs. 241±74 pmol/min/m2, p=0.004) second-phase ISR following dorzagliatin versus placebo. Dorzagliatin significantly improved GS in GCK-MODY (51±21 vs. 33­±13 pmol/min/m2 per mmol/L p=0.028) with an upward and leftward shift in ISR-glucose response. In T2D, basal ISR was significantly improved following dorzagliatin (102±57 vs. 60±42, p=0.018) with smaller increases in second phase ISR and GS. Dorzagliatin improves second phase ISR and GS, with larger effects in GCK-MODY than T2D. Disclosure E.Chow: Research Support; Hua Medicine, Medtronic, Powder Pharmaceuticals Inc., Speaker's Bureau; Novartis AG, Sanofi. L.Chen: Employee; Hua Medicine. J.C.Chan: Board Member; Asia Diabetes Foundation, Consultant; Bayer AG, Boehringer Ingelheim International GmbH, Celltrion, Merck Sharp &amp; Dohme Corp., Roche Diabetes Care, Viatris Inc., Research Support; Applied Therapeutics, AstraZeneca, Eli Lilly and Company, Hua Medicine, Servier Laboratories, Stock/Shareholder; GemVCare Ltd. K.Wang: None. C.K.P.Lim: None. S.Tsoi: None. B.Fan: None. A.Luk: None. R.C.Ma: Other Relationship; Bayer AG, Boehringer Ingelheim International GmbH, Research Support; AstraZeneca, Bayer AG, Novo Nordisk A/S, Pfizer Inc., Tricida, Inc. E.Ferrannini: Advisory Panel; Boehringer Ingelheim International GmbH, Novo Nordisk, Oramed Pharmaceuticals, Consultant; Elgia Therapeutics, Research Support; Janssen Research &amp; Development, LLC, Oramed Pharmaceuticals, Sanofi-Aventis U.S., Speaker's Bureau; Boehringer Ingelheim International GmbH. A.Mari: Consultant; Lilly, Research Support; Lilly. Funding Hua Medicine Investigator Initiated Clinical Research

Evaluation of pregnancy outcomes in women with GCK-MODY.

To determine the fetal and maternal outcomes in pregnant women with Glucokinase-Maturity onset diabetes of the young (GCK-MODY). We studied the obstetric and perinatal outcomes in 99 pregnancies of 34 women with GCK-MODY. The mutation status of the offspring was known in 29 and presumed in 33. Clinical outcomes were determined and compared between affected (n=39) and unaffected (n=23) offspring. 59% of pregnancies were treated with diet alone and 41% received insulin. Birthweight, percentage of large for gestational age (LGA) and caesarean section (CS) in GCK-unaffected offspring was significantly higher than in GCK-affected offspring (4.0±0.7 vs. 3.4±0.4kg, p=0.001), 15 (65%) vs. 5(13%) (p=0.00006) and 17 (74%) vs. 11 (28%) (p=0.001), respectively. We observed an earlier gestational age at delivery on insulin in unaffected offspring (38.3±1.0 vs. 39.5±1.5 weeks, p=0.03) with no significant change in LGA (9 (82%) vs. 6 (50%); p=0.12), and a higher rate of CS (8 [73%] vs. 3 [11%]; p<0.001), and no change in small for gestational age (0 [0%] vs. 4 [14%]; p=0.30) in affected offspring. Insulin therapy in unaffected offspring did not reduce LGA and was associated with earlier gestational age at delivery. Insulin treatment in GCK-affected offspring was associated with an increased incidence of CS, but did not adversely affect fetal outcome. Fetal genotype determines birthweight rather than treatment. Pre-pregnancy diagnosis of GCK-MODY, use of continuous glucose monitoring and non-invasive fetal genotyping may enable further investigation of targeted therapy in this condition.

Localized increases in CEPT1 and ATGL elevate plasmalogen phosphatidylcholines in HDLs contributing to atheroprotective lipid profiles in hyperglycemic GCK-MODY

Glucokinase-maturity onset diabetes of the young (GCK-MODY) represents a rare genetic disorder due to mutation in the glucokinase (GCK) gene. The low incidence of vascular complications in GCK-MODY makes it a natural paradigm for interrogating molecular mechanisms promoting vascular health under prolonged hyperglycemia. Clinical rate of misdiagnosis has remained high, and a reliable serum lipid biomarker that precedes genetic screening can facilitate correct diagnosis and treatment. Herein, we comprehensively quantitated 565 serum lipids from 25 classes in 105 subjects (42 nondiabetic controls, 30 GC K-MODY patients, 33 drug-naïve, and newly-onset T2D patients). At false-discovery rate (FDR) < 0.05, several phosphatidylcholines (PCs) and plasmalogen PCs were specifically increased in GCK-MODY, while triacylglycerols (TAGs) and diacylglycerols (DAGs) were reduced. Correlation matrices between lipids uncovered coregulation between plasmalogen PCs (PCps) and glycerolipid precursors was distinctly enhanced in GCK-MODY compared to T2D. Strengthened positive correlations between serum PCps and circulating HDLs was specifically observed in hyperglycemic subjects (i.e. T2D and GCK-MODY) compared to normglycemic controls, suggesting that HDL-PCps may elicit distinct physiological effects under hyperglycemia. Amongst GCK-MODY patients, individuals harboring variants of GCK mutations with elevated PCps also exhibited higher HDLs. Isolated HDLs displayed localized increases (p < 0.05) in very-long-chain PUFA-PCs and PCps in GCK-MODY. Protein analyses revealed elevated levels of HDL-resident ATGL (P = 0.003) and CEPT1 (P < 0.0001), which mediate critical steps of PCps production along the TAG-DAG-PC axis, in GCK-MODY relative to T2D. A panel of four lipids differentiated GCK-MODY from T2D with AUC of 0.950 (95% CI 0.903–9.997). This study provides the first evidence that enhanced recruitment of CEPT1 and ATGL onto HDLs essentially underlie the atheroprotective profiles associated with GCK-MODY. Resultant increases in the production of HDL-PCps and PUFA-PCs provides an active, circulating form of protection towards the vasculature of GCK-MODY, thereby lowering the incidence of vascular complications despite chronic exposure to hyperglycemia since birth.

Absence of Islet Autoantibodies and Modestly Raised Glucose Values at Diabetes Diagnosis Should Lead to Testing for MODY: Lessons From a 5-Year Pediatric Swedish National Cohort Study.

OBJECTIVEIdentifying maturity-onset diabetes of the young (MODY) in pediatric populations close to diabetes diagnosis is difficult. Misdiagnosis and unnecessary insulin treatment are common. We aimed to identify the discriminatory clinical features at diabetes diagnosis of patients with glucokinase (GCK), hepatocyte nuclear factor-1A (HNF1A), and HNF4A MODY in the pediatric population.RESEARCH DESIGN AND METHODSSwedish patients (n = 3,933) aged 1–18 years, diagnosed with diabetes May 2005 to December 2010, were recruited from the national consecutive prospective cohort Better Diabetes Diagnosis. Clinical data, islet autoantibodies (GAD insulinoma antigen-2, zinc transporter 8, and insulin autoantibodies), HLA type, and C-peptide were collected at diagnosis. MODY was identified by sequencing GCK, HNF1A, and HNF4A, through either routine clinical or research testing.RESULTSThe minimal prevalence of MODY was 1.2%. Discriminatory factors for MODY at diagnosis included four islet autoantibody negativity (100% vs. 11% not-known MODY; P = 2 × 10−44), HbA1c (7.0% vs. 10.7% [53 vs. 93 mmol/mol]; P = 1 × 10−20), plasma glucose (11.7 vs. 26.7 mmol/L; P = 3 × 10−19), parental diabetes (63% vs. 12%; P = 1 × 10−15), and diabetic ketoacidosis (0% vs. 15%; P = 0.001). Testing 303 autoantibody-negative patients identified 46 patients with MODY (detection rate 15%). Limiting testing to the 73 islet autoantibody-negative patients with HbA1c <7.5% (58 mmol/mol) at diagnosis identified 36 out of 46 (78%) patients with MODY (detection rate 49%). On follow-up, the 46 patients with MODY had excellent glycemic control, with an HbA1c of 6.4% (47 mmol/mol), with 42 out of 46 (91%) patients not on insulin treatment.CONCLUSIONSAt diagnosis of pediatric diabetes, absence of all islet autoantibodies and modest hyperglycemia (HbA1c <7.5% [58 mmol/mol]) should result in testing for GCK, HNF1A, and HNF4A MODY. Testing all 12% patients negative for four islet autoantibodies is an effective strategy for not missing MODY but will result in a lower detection rate. Identifying MODY results in excellent long-term glycemic control without insulin.

Diagnosis and management of glucokinase monogenic diabetes in pregnancy: current perspectives.

Glucokinase–maturity-onset diabetes of the young (GCK-MODY) is an autosomal dominant disorder caused by heterozygous inactivating GCK gene mutations. GCK-MODY is one the most common MODY subtypes, affecting 0.1% of the population and 0.4–1% of women with gestational diabetes mellitus. Glucokinase is predominantly expressed in pancreatic beta cells and catalyzes the phosphorylation of glucose to glucose-6-phosphate. The unique kinetics of glucokinase enable it to change the rate of glucose phosphorylation according to the glucose concentration, thereby regulating insulin secretion. Individuals with GCK-MODY have mildly elevated fasting blood glucose levels (5.5–8.0 mmol/L) and regulate glucose perturbations to a higher set-point, resulting in a relatively flat glucose profile on a 75 g oral glucose tolerance test. The hyperglycemia is usually subclinical and may only be detected on incidental glucose testing. It is important to correctly identify GCK-MODY as the clinical course and management differs substantially from other types of diabetes. Diabetes-related complications are relatively uncommon, so glucose-lowering treatment is not usually required. The exception is pregnancy, where fetal growth and therefore glucose-lowering treatment are predominantly determined by whether or not the fetus inherits the GCK mutation. The fetal genotype is not usually known but can be inferred from serial fetal ultrasound measurements. If there is evidence of accelerating fetal abdominal circumference on serial ultrasounds, the fetus is assumed to not have the GCK mutation and treatment of maternal hyperglycemia is indicated to reduce the risk of macrosomia, Caesarean section and neonatal hypoglycemia. If there is no evidence of accelerating fetal growth, the fetus is assumed to have inherited the GCK mutation and will have a similarly elevated glucose set-point as their mother, so maternal hyperglycemia is not treated. With recent advances in genetic technology, such as next-generation sequencing and noninvasive fetal genotyping, the detection and management of GCK-MODY in pregnancy should continue to improve.

Současné možnosti léčby Maturity-Onset Diabetes of the Young (MODY)

The discovery of MODY (Maturity-Onset Diabetes of the Young) and the elucidation of its heritability enabled more precise clinical characteristics of different MODY subtypes and led to understanding that glucokinase MODY (GCK-MODY) is not associated with vascular complications in long term follow-up, whereas MODY of transcription factors (e.g. HNF1A-MODY) is in case of bad metabolic control connected with the acceleration of particularly microvascular complications. There is a strong evidence of the needlessness of any specific antidiabetic treatment in prognosticaly favourable GCK-MODY (except for the pregnancy). On the contrary, in MODY of transcription factors, including the most common one - HNF1A-MODY, the treatment, traditionally based on sulphonylurea derivatives (and after their failure on insulin) is required. Due to wider spectrum of available antidiabetic agents offering individualization of the treatment, the question of efficacy of other antidiabetic agents in MODY patients arises. This review article summarizes current knowledge of therapeutic options in patients with MODY.Key words: insulin - MODY - oral hypoglycemic drugs - treatment.

Genetic and clinical characteristics of Chinese children with Glucokinase-maturity-onset diabetes of the young (GCK-MODY)

BackgroundThere is scarcity of information on the clinical features and genetics of glucokinase-maturity-onset diabetes of the young (GCK-MODY) in China. The aim of the study was to investigate the clinical and molecular characteristics of Chinese children with GCK-MODY.MethodsEleven children with asymptomatic hyperglycemia and clinically suspected GCK-MODY were identified from the database of children with diabetes in the biggest children’s hospital in South China. Clinical data were obtained from medical records. Blood was collected from the patients and their parents for glucokinase (GCK) gene analysis. Parents without diabetes were tested for fasting glucose and HbA1c. Clinical information and blood for GCK gene analysis were obtained from grandparents with diabetes. GCK gene mutational analysis was performed by polymerase chain reaction and direct sequencing. Patients without a GCK gene mutation were screened by targeted next-generation sequencing (NGS) technology for other MODY genes.ResultsNine children tested positive for GCK gene mutations while two were negative. The nine GCK-MODY patients were from unrelated families, aged 1 month to 9 years and 1 month at first detection of hyperglycaemia. Fasting glucose was elevated (6.1–8.5 mmol/L), HbA1c 5.2–6.7% (33.3–49.7 mmol/mol), both remained stable on follow-up over 9 months to 5 years. Five detected mutations had been previously reported: p.Val182Met, c.679 + 1G > A, p.Gly295Ser, p.Arg191Gln and p.Met41Thr. Four mutations were novel: c.483 + 2 T > A, p.Ser151del, p.Met57GlyfsX29 and p.Val374_Ala377del. No mutations were identified in the other two patients, who were also tested by NGS.ConclusionsGCK gene mutations are detected in Chinese children and their family members with typical clinical features of GCK-MODY. Four novel mutations are detected.

Phenotype Heterogeneity in Glucokinase-Maturity-Onset Diabetes of the Young (GCK-MODY) Patients.

Objective:The aim of the study was to evaluate the clinical phenotypes of glucokinase-maturity-onset diabetes of the young (GCK-MODY) pediatric patients from Southwest Poland and to search for phenotype-genotype correlations.Methods:We conducted a retrospective analysis of data on 37 CGK-MODY patients consisting of 21 girls and 16 boys of ages 1.9-20.1 (mean 12.5±5.2) years, treated in our centre in the time period between 2002 and 2013.Results:GCK-MODY carriers were found in a frequency of 3% among 1043 diabetes mellitus (DM) patients and constituted the second most numerous group of DM patients, following type 1 DM, in our centre. The mean age of GCK-MODY diagnosis was 10.4±4.5 years. The findings leading to the diagnosis were impaired fasting glucose (IFG) (15/37), symptoms of hyperglycemia (4/37), and a GCK-MODY family history (18/37). Mean fasting blood glucose level was 6.67±1.64 mmol/L. In the sample, there were patients with normal values (4/37), those with DM (10/37), and IFG (23/37). In OGTT, 120 min glucose level was normal in 8, diabetic in 2, and characteristic for glucose intolerance in 27 of the 37 cases. Twelve of the 37 cases (32%) were identified as GCK-MODY carriers. In the total group, mean C-peptide level was 2.13±0.65 ng/mL and HbA1c was 6.26±0.45% (44.9±-18 mmol/mol). Thirty-two patients had a family history of DM. DM autoantibodies were detected in two patients. The most common mutations were p.Gly318Arg (11/37) and p.Val302Leu (8/37). There was no correlation between type of mutations and plasma glucose levels.Conclusion:The phenotype of GCK-MODY patients may vary from those characteristic for other DM types to an asymptomatic state with normal FG with no correlation with genotype.

A single dose of dapagliflozin, an SGLT-2 inhibitor, induces higher glycosuria in GCK- and HNF1A-MODY than in type 2 diabetes mellitus

AimsSGLT2 inhibitors are a new class of oral hypoglycemic agents used in type 2 diabetes (T2DM). Their effectiveness in maturity onset diabetes of the young (MODY) is unknown. We aimed to assess the response to a single dose of 10 mg dapagliflozin in patients with Hepatocyte Nuclear Factor 1 Alpha (HNF1A)-MODY, Glucokinase (GCK)-MODY, and type 2 diabetes.MethodsWe examined 14 HNF1A-MODY, 19 GCK-MODY, and 12 type 2 diabetes patients. All studied individuals received a single morning dose of 10 mg of dapagliflozin added to their current therapy of diabetes. To assess the response to dapagliflozin we analyzed change in urinary glucose to creatinine ratio and serum 1,5-Anhydroglucitol (1,5-AG) level.ResultsThere were only four patients with positive urine glucose before dapagliflozin administration (one with HNF1A-MODY, two with GCK-MODY, and one with T2DM), whereas after SGLT-2 inhibitor use, glycosuria occurred in all studied participants. Considerable changes in mean glucose to creatinine ratio after dapagliflozin administration were observed in all three groups (20.51 ± 12.08, 23.19 ± 8.10, and 9.84 ± 6.68 mmol/mmol for HNF1A-MODY, GCK-MODY, and T2DM, respectively, p < 0.001 for all comparisons). Post-hoc analysis revealed significant differences in mean glucose to creatinine ratio change between type 2 diabetes and each monogenic diabetes in response to dapagliflozin (p = 0.02, p = 0.003 for HNF1-A and GCK MODY, respectively), but not between the two MODY forms (p = 0.7231). Significant change in serum 1,5-AG was noticed only in T2DM and it was −6.57 ± 7.34 mg/ml (p = 0.04).ConclusionsA single dose of dapagliflozin, an SGLT-2 inhibitor, induces higher glycosuria in GCK- and HNF1A-MODY than in T2DM. Whether flozins are a valid therapeutic option in these forms of MODY requires long-term clinical studies.

Identification of Maturity-Onset Diabetes of the Young Caused by Glucokinase Mutations Detected Using Whole-Exome Sequencing.

Glucokinase maturity-onset diabetes of the young (GCK-MODY) represents a distinct subgroup of MODY that does not require hyperglycemia-lowering treatment and has very few diabetes-related complications. Three patients from two families who presented with clinical signs of GCK-MODY were evaluated. Whole-exome sequencing was performed and the effects of the identified mutations were assessed using bioinformatics tools, such as PolyPhen-2, SIFT, and in silico modeling. We identified two mutations: p.Leu30Pro and p.Ser383Leu. In silico analyses predicted that these mutations result in structural conformational changes, protein destabilization, and thermal instability. Our findings may inform future GCK-MODY diagnosis; furthermore, the two mutations detected in two Korean families with GCK-MODY improve our understanding of the genetic basis of the disease.

A novel genetic mutation in a Turkish family with GCK-MODY

Glucokinase-maturity-onset diabetes of the young (GCK-MODY) is an autosomal dominantly inherited disease caused by heterozygous inactivating mutations in the glucokinase gene. It usually presents with mild fasting hyperglycemia. Here, we present an obese patient and her family with GCK-MODY caused by a novel heterozygous p.E51*(c.151.G>T) mutation in the GCK gene.

Recognition and Management of Individuals With Hyperglycemia Because of a Heterozygous Glucokinase Mutation.

Glucokinase-maturity-onset diabetes of the young (GCK-MODY), also known as MODY2, is caused by heterozygous inactivating mutations in the GCK gene. GCK gene mutations are present in ∼1 in 1,000 of the population, but most are not diagnosed. They are common causes of MODY (10-60%): persistent incidental childhood hyperglycemia (10-60%) and gestational diabetes mellitus (1-2%). GCK-MODY has a unique pathophysiology and clinical characteristics, so it is best considered as a discrete genetic subgroup. People with GCK-MODY have a defect in glucose sensing; hence, glucose homeostasis is maintained at a higher set point resulting in mild, asymptomatic fasting hyperglycemia (5.4-8.3 mmol/L, HbA1c range 5.8-7.6% [40-60 mmol/mol]), which is present from birth and shows slight deterioration with age. Even after 50 years of mild hyperglycemia, people with GCK-MODY do not develop significant microvascular complications, and the prevalence of macrovascular complications is probably similar to that in the general population. Treatment is not recommended outside pregnancy because glucose-lowering therapy is ineffective in people with GCK-MODY and there is a lack of long-term complications. In pregnancy, fetal growth is primarily determined by whether the fetus inherits the GCK gene mutation from their mother. Insulin treatment of the mother is only appropriate when increased fetal abdominal growth on scanning suggests the fetus is unaffected. The impact on outcome of maternal insulin treatment is limited owing to the difficulty in altering maternal glycemia in these patients. Making the diagnosis of GCK-MODY through genetic testing is essential to avoid unnecessary treatment and investigations, especially when patients are misdiagnosed with type 1 or type 2 diabetes.

Circulating ghrelin level is higher in HNF1A-MODY and GCK-MODY than in polygenic forms of diabetes mellitus.

Ghrelin is a hormone that regulates appetite. It is likely to be involved in the pathophysiology of varying forms of diabetes. In animal studies, the ghrelin expression was regulated by the hepatocyte nuclear factor 1 alpha (HNF1A). Mutations of the HNF1A gene cause maturity onset diabetes of the young (MODY). We aimed to assess the circulating ghrelin levels in HNF1A–MODY and in other types of diabetes and to evaluate its association with HNF1A mutation status. Our cohort included 46 diabetic HNF1A gene mutation carriers, 55 type 2 diabetes (T2DM) subjects, 42 type 1 diabetes (T1DM) patients, and 31 glucokinase (GCK) gene mutation carriers with diabetes as well as 51 healthy controls. Plasma ghrelin concentration was measured using the immunoenzymatic assay with polyclonal antibody against the C-terminal fragment of its acylated and desacylated forms. Ghrelin concentrations were 0.75 ± 0.32, 0.70 ± 0.21, 0.50 ± 0.20, and 0.40 ± 0.16 ng/ml in patients with HNF1A–MODY, GCK–MODY, T1DM, and T2DM, respectively. The ghrelin levels were higher in HNF1A–MODY and GCK–MODY than in T1DM and T2DM (p < 0.001 for all comparisons) but lower than in non-diabetic controls (1.02 ± 0.29 ng/ml, p < 0.001 for both comparisons). In the multivariate linear model, the differences between both MODY groups and common diabetes types remained significant. Analysis by a HNF1A mutation type indicated that ghrelin concentration is similar in patients with different types of sequence differences. Plasma ghrelin level is higher in HNF1A–MODY and GCK–MODY than in the common polygenic forms of diabetes.