Gut microbiota, behavior, and nutrition after type 1 diabetes diagnosis: A longitudinal study for supporting data in the metabolic control.

Introduction: Type 1 diabetes (T1D) risk involves genetic susceptibility but also epigenetics, environment, and behaviors. Appropriate metabolic control, especially quickly after the diagnosis, is crucial for the patient quality of life. Methods: This study aimed to produce a quantitative comparison of the behavior, nutrition habits, and gut microbiota composition between the onset and the 1-year follow-up in 35 children with T1D. Results and discussion: At follow-up, with the metabolic control, many parameters improved significantly, with respect to the onset, such as glycated hemoglobin (-19%), body mass index (BMI), and also nutritional behaviors, such as normal calorie intake (+6%), carbohydrate intake (-12%), extra portion request (-4%), and meals distribution during the day. Moreover, glycated hemoglobin decrement correlated with both total and rapid absorption carbohydrate intake (Spearman's rho = 0.288, 95% CI 0.066-0.510, p = 0.013), showing as the nutritional behavior supported the insulin therapy efficiency. The next-generation sequencing (NGS) analysis of microbiota revealed abundance differences for Ruminococcus bromii and Prevotella copri (higher at onset, p < 0.001) and the genera Succinivibrio and Faecalibacterium (lower at onset, p < 0.001), as a consequence of nutritional behavior, but it was not the only changing driver. The qRT-PCR analysis showed significant variations, in particular for Bacteroidetes and Bifidobacterium spp. (+1.56 log gene copies/g stool at follow-up, p < 0.001). During the year, in 11% of the patients, severe clinical episodes occurred (hypoglycemic or ketoacidosis). The likelihood of a severe hypoglycemic episode was modulated when the Methanobrevibacter smithii amount increased (odds ratio 3.7, 95% CI 1.2-11.4, p = 0.026). Integrated evaluation, including nutritional behavior and microbiota composition, could be considered predictive of the metabolic control management for children cohort with a recent diagnosis of T1D.

Vitamin D and ω-3 Polyunsaturated Fatty Acids towards a Personalized Nutrition of Youth Diabetes: A Narrative Lecture.

After the discovery of insulin, nutrition has become central in the management of diabetes in order to limit glycemic rise after meals, optimize metabolic control, and prevent complications. Over the past one hundred years, international scientific societies have consecutively refined nutritional needs and optimized food intake for the treatment of diabetes. In particular, over the past century, nutrition applied with pumps for the administration of insulin and continuous glucose monitoring have allowed substantial advancement in the treatment of type 1 diabetes mellitus. The role of some substances, such as vitamin D and n-3 polyunsaturated fatty acids, have been proposed without univocal conclusions, individually or in combination, or in the diet, to improve the nutrition of type 1 and type 2 diabetes. This second condition, which is highly associated with overweight, should be prevented from childhood onwards. Personalized nutrition could bypass the problem, reaching a scientific conclusion on the individual subject. This article focuses on childhood and adolescent diabetes, aims to provide a narrative summary of nutrition over the past century, and promotes the concept of personalized nutrition to pediatricians and pediatric diabetologists as a possible tool for the treatment of type 1 diabetes and the prevention of type 2 diabetes.

Risk factors for type 1 diabetes, including environmental, behavioural and gut microbial factors: a case-control study.

Type 1 diabetes (T1D) is a common autoimmune disease that is characterized by insufficient insulin production. The onset of T1D is the result of gene-environment interactions. Sociodemographic and behavioural factors may contribute to T1D, and the gut microbiota is proposed to be a driving factor of T1D. An integrated preventive strategy for T1D is not available at present. This case-control study attempted to estimate the exposure linked to T1D to identify significant risk factors for healthy children. Forty children with T1D and 56 healthy controls were included in this study. Anthropometric, socio-economic, nutritional, behavioural, and clinical data were collected. Faecal bacteria were investigated by molecular methods. The findings showed, in multivariable model, that the risk factors for T1D include higher Firmicutes levels (OR 7.30; IC 2.26-23.54) and higher carbohydrate intake (OR 1.03; IC 1.01-1.05), whereas having a greater amount of Bifidobacterium in the gut (OR 0.13; IC 0.05 - 0.34) was a protective factor for T1D. These findings may facilitate the development of preventive strategies for T1D, such as performing genetic screening, characterizing the gut microbiota, and managing nutritional and social factors.

Vitamin D Supplementation Modulates ICOS+ and ICOS- Regulatory T Cell in Siblings of Children With Type 1 Diabetes.

OBJECTIVES: Vitamin D plays an immunoregulatory activity. The aim of this study was to assess the correlation between blood serum 25(OH)D levels and Th17 and Treg circulating subsets, mainly Treg/inducible costimulatory-positive (ICOS+), which seems to have a protective role in autoimmunity, in children with type 1 diabetes mellitus (T1D) and their healthy siblings (S). The secondary aim was to evaluate the impact of vitamin D supplementation on these subsets. PATIENTS AND METHODS: 22 T1D and 33 S were enrolled. Glucose, hemoglobin A1c, 25 OH vitamin D (25[OH]D), T helper type 17 (Th17; CD4+CCR6+), regulatory T cells (Treg; CD4+CD25+Foxp3+), and Treg/ICOS+ cells were evaluated. According to human leukocyte antigen (HLA) haplotypes, subjects were classified as "at risk" (HLA+), "protective haplotypes" (HLA-; "nested controls"), and "undetermined" (HLAUND). T1D and S subjects were supplemented with cholecalciferol 1000 IU/die and evaluated after 6 months. RESULTS: Vitamin D insufficiency (74.4%) and deficiency (43%) were frequent. S subjects with 25(OH)D levels <25 nmol/L had Th17, Treg (p < 0.01), and Treg/ICOS+ (P < 0.05) percentages higher than subjects with 25(OH)D >75 nmol/L. Treg/ICOS+ percentages (P < 0.05) were higher in HLA- S subjects compared to percentages observed in S with T1D. At baseline, in S subjects, a decreasing trend in Th17 and Treg/ICOS+ values (P < 0.05) from vitamin D deficiency to sufficiency was observed; 25(OH)D levels were negative predictors of Treg/ICOS+ (R2 = 0.301) and Th17 percentages (R2 = 0.138). After 6 months, supplemented S subjects showed higher 25(OH)D levels (P < 0.0001), and lower Th17 (P < 0.0001) and Treg/ICOS+ (P < 0.05) percentages than at baseline; supplemented T1D patients only had a decrease in Th17 levels (P < 0.05). CONCLUSION: Serum 25(OH)D levels seem to affect Th17 and Treg cell subsets in S subjects, consistent with its immunomodulating role. HLA role should be investigated in a larger population.

Microbiota, epidemiological and nutritional factors related to ketoacidosis at the onset of type 1 diabetes.

AIMS: The incidence of type 1 diabetes has increased over the last decades. The pathological pathway is not yet clear, even if genetic and environmental risk factors are known. An early diagnosis can avoid ketoacidosis and its complications. This work aims to discuss the determinants of both ketoacidosis at the onset and access by hospital emergency departments without a suspected diagnosis. METHODS: An observational bi-centric prospective study was conducted in Northern Italy, on a paediatric population including Italian and migrant patients at the diabetes onset. Seventy-four type 1 diabetes patients, both Italian and migrant, were included in the study. Anthropometric, socio-economic, behavioural, clinical data were collected, and microbiota analyses were performed using stool samples. RESULTS: Regular physical activity is associated with lower ketoacidosis incidence at onset (OR 0.33 95% CI 0.12-0.95 p < 0.05), as is higher blood vitamin D level (OR 0.92 95% CI 0.85-0.99 p < 0.05). Moreover, a higher weaning age (OR 0.49 95% CI 0.27-0.89 p < 0.05), higher vitamin D level (OR 0.90 95% CI 0.83-0.98 p < 0.05) and a higher level of Akkermansia muciniphila (OR 0.46 95% CI 0.25-0.87 p < 0.05) are associated factors to lower frequency of type 1 diabetes onset without a suspected diagnosis. Diabetes migrant status is not a risk factor for severe type 1 diabetes onset; on the other hand, some protective factors are significantly more diffused among Italians, such as regular sport activity and non-critical vitamin D levels. CONCLUSION: Behavioural and nutritional data, such as microbiota bio-indicators, seem to be useful to identify an at-risk population to prevent ketoacidosis and its severe complications.

Nutritional behavior in Italian and immigrant children.

BACKGROUND: There are 1.2 million of immigrant children living in Italy. However, data on their nutritional habits are limited. The aim of this study was to assess the nutritional profile in a cohort of both Italian and immigrant children. METHODS: The study included 86 children aged 5-15 consecutively enrolled from January 2016 to May 2017 within a larger epidemiological study on determinants of diabetes. Immigrant state was defined on the basis of the parent origin. Data on nutritional profile, frequency of food group consumption, and eating habits were collected using the 24-hour dietary recall method and a questionnaire. Anthropometric parameters were measured. RESULTS: In the cohort of immigrant children there was a higher prevalence of both overweight (27.3 vs. 14.1%) and obesity (18.2 vs. 3.1%) subjects and a greater total calorie intake compared to Italian children, mainly due to excess simple carbohydrate intake. Immigrant children had a higher consumption of sweets, snacks, and drinks with added sugar. Moreover, unhealthy habits, such as eating alone and eating while watching TV, were more frequent among immigrant children. CONCLUSIONS: In this cohort, immigrant children had a higher prevalence of overweight/obesity possibly due to less healthy nutritional habits. Culturally-tailored nutritional interventions may help preventing the development of obesity-related diseases in this population.

Vitamin D and ω-3 Supplementations in Mediterranean Diet During the 1st Year of Overt Type 1 Diabetes: A Cohort Study.

Vitamin D and omega 3 fatty acid (ω-3) co-supplementation potentially improves type 1 diabetes (T1D) by attenuating autoimmunity and counteracting inflammation. This cohort study, preliminary to a randomized control trial (RCT), is aimed at evaluating, in a series of T1D children assuming Mediterranean diet and an intake of cholecalciferol of 1000U/day from T1D onset, if ω-3 co-supplementation preserves the residual endogen insulin secretion (REIS). Therefore, the cohort of 22 "new onsets" of 2017 received ω-3 (eicosapentenoic acid (EPA) plus docosahexaenoic acid (DHA), 60 mg/kg/day), and were compared retrospectively vs. the 37 "previous onsets" without ω-3 supplementation. Glicosilated hemoglobin (HbA1c%), the daily insulin demand (IU/Kg/day) and IDAA1c, a composite index (calculated as IU/Kg/day × 4 + HbA1c%), as surrogates of REIS, were evaluated at recruitment (T0) and 12 months later (T12). In the ω-3 supplemented group, dietary intakes were evaluated at T0 and T12. As an outcome, a decreased insulin demand (p < 0.01), particularly as pre-meal boluses (p < 0.01), and IDAA1c (p < 0.05), were found in the ω-3 supplemented group, while HbA1c% was not significantly different. Diet analysis in the ω-3 supplemented group, at T12 vs. T0, highlighted that the intake of arachidonic acid (AA) decreased (p < 0.01). At T0, the AA intake was inversely correlated with HbA1c% (p < 0.05; r;. 0.411). In conclusion, the results suggest that vitamin D plus ω-3 co-supplementation as well as AA reduction in the Mediterranean diet display benefits for T1D children at onset and deserve further investigation.

Vitamin D Deficiency and Glycemic Status in Children and Adolescents with Type 1 Diabetes Mellitus.

BACKGROUND: Vitamin D (25OHD) effects on glycemic control are unclear in children and adolescents with type 1 diabetes. Aims of this study were to investigate 25OHD status among children with T1DM and its relationship with insulin sensitivity and glycemic status. SUBJECTS AND METHODS: A cross sectional study was carried out between 2008-2014. A total of 141 patients had a T1DM >12 months diagnosis and were enrolled in the present study. Of these 35 (24.8%) were migrants and 106 (75.2%) Italians (T2). We retrospectively analyzed data at the onset of the disease (T0)(64 subjects) and 12-24 months before the last visit (T1,124 subjects). Fasting glucose, glycated hemoglobin (HbA1c), 25OHD levels and daily insulin requirement were evaluated and Cholecalciferol 1000 IU/day supplementation for the management of vitamin D insufficiency (<75 nmol/L) was systematically added. RESULTS: A generalized 25OHD insufficiency was found at each study time, particularly in migrants. At T0, the 25OHD levels were inversely related to diabetic keto-acidosis (DKA) severity (p<0.05). At T1 and T2, subjects with 25OHD ≤25nmol/L (10 ng/mL) showed higher daily insulin requirement (p<0.05) and HbA1c values (p<0.01) than others vitamin D status. The 25OHD levels were negatively related with HbA1c (p<0.001) and daily insulin dose (p<0.05) during follow up. There was a significant difference in 25OHD (p<0.01) between subjects with different metabolic control (HbA1c <7.5%,7.5-8%,>8%), both at T1 and T2. In supplemented subjects, we found a significant increase in 25OHD levels (p<0.0001) and decrease of HbA1c (p<0.001) between T1 and T2, but this was not significant in the migrants subgroup. Multivariate regression analysis showed a link between HbA1c and 25OHD levels (p<0.001). CONCLUSIONS: Children with T1DM show a generalized 25OHD deficiency that impact on metabolic status and glycemic homeostasis. Vitamin D supplementation improves glycemic control and should be considered as an additional therapy.

Ketoacidosis at diagnosis in childhood-onset diabetes and the risk of retinopathy 20years later.

AIMS: To investigate on the relationship between severity of ketoacidosis, an important risk factor for C-peptide preservation, and long-term microvascular complications in childhood-onset type 1 diabetes mellitus (T1DM). METHODS: 230 childhood-onset diabetic patients (177 pre-pubertal), aged 7.0±3.8years followed for at least 15years after their diagnosis, were enrolled. Clinical and laboratory data at diagnosis, and C-peptide levels in a subset of patients, were compared with the severity of retinopathy and nephropathy, after a mean of 19.6±3.8years of disease. Digital retinal photographs were taken in all patients, and centrally graded. Repeated measurements of HbA1c and microalbuminuria for the whole duration of diabetes were collected in over half of the cases. RESULTS: Out of 230 patients, those with the lowest age at diagnosis had the most severe DKA and clinical conditions (p<0.05), and lower C-peptide levels (p<0.0001) at diagnosis. There was a significant relationship between pH and clinical severity (r=-0.783, p<0.0001), and between pH and C-peptide levels (r=0.278, p<0.05). The severity of ketoacidosis had no relationship with subsequent lifetime HbA1c values and long-term microvascular complications. In logistic regression analysis, the only variables that independently influenced severity of retinopathy were lifetime HbA1c (B=0.838, p<0.001), duration of disease (B=0.208, p<0.005) and age at diagnosis (B=0.116, p<0.05). CONCLUSIONS: The degree of metabolic derangement at diagnosis is not associated with retinopathy and nephropathy in childhood-onset T1DM. Age at diagnosis seems to be an important variable to be considered when evaluating the long-term effects of residual beta-cell function.

High Prevalence of Vitamin D Deficiency in Native versus Migrant Mothers and Newborns in the North of Italy: A Call to Act with a Stronger Prevention Program.

BACKGROUND: Vitamin D status during pregnancy is related to neonatal vitamin D status. Vitamin D deficiency has been associated with an increased risk of rickets in children and osteomalacia in adults. Aim of this study was to investigate 25OHD levels in maternal serum and in neonatal blood spots in native and migrant populations living in Novara (North Italy, 45°N latitude). METHODS AND FINDINGS: We carried out a cross sectional study from April 1st 2012 to March 30th 2013, in a tertiary Care Center. Maternal blood samples after delivery and newborns' blood spots were analyzed for 25OHD levels in 533 pairs. Maternal country of origin, skin phototype, vitamin D dietary intake and supplementation during pregnancy were recorded. Multivariate regression analysis, showed a link between neonatal and maternal 25OHD levels (R-square:0.664). Severely deficient 25OHD values (<25 nmol/L) were found in 38% of Italian and in 76.2% of migrant's newborns (p <0.0001), and in 18% of Italian and 48,4% of migrant mothers (p <0.0001) while 25OHD deficiency (≥25 and <50 nmol/L) was shown in 40.1% of Italian and 21.7% of migrant's newborns (p <0.0001), and in 43.6% of Italian and 41.3% of migrant mothers (p <0.0001). Italian newborns and mothers had higher 25OHD levels (34.4±19.2 and 44.9±21.2 nmol/L) than migrants (17.7±13.7 and 29.7±16.5 nmol/L; p<0.0001). A linear decrease of 25OHD levels was found with increasing skin pigmentation (phototype I 42.1 ±18.2 vs phototype VI 17.9±10.1 nmol/l; p<0.0001). Vitamin D supplementation resulted in higher 25OHD values both in mothers and in their newborns (p<0.0001). CONCLUSIONS: Vitamin D insufficiency in pregnancy and in newborns is frequent especially among migrants. A prevention program in Piedmont should urgently be considered and people identified as being at risk should be closely monitored. Vitamin D supplementation should be taken into account when considering a preventative health care policy.

Vitamin D levels at birth and risk of type 1 diabetes in childhood: a case-control study.

AIMS: To assess whether vitamin D levels at birth were associated with risk of having type 1 diabetes up to 10 years of age and the potential modifier effect of ethnic group. METHODS: The Piedmont Diabetes Registry and the Newborn Screening Regional data were linked to identify cases (n = 67 incident children aged ≤10 years at diabetes onset, 2002-2012) and up to five controls (n = 236) matched for birthday and ethnic group. Cards with neonatal blood spot were used and 25-hydroxyvitamin D(3) assessed with tandem mass spectroscopy. RESULTS: In conditional logistic regression, OR for unit increment of log vitamin D was 0.78 (95 % CI 0.56-1.10). Vitamin D was significantly lower in migrant than in Italian control newborn babies (p < 0.0001), and interaction between vitamin D and migrant status was statistically significant (p = 0.04). Compared to migrant newborns babies with vitamin D ≥ 2.14 ng/ml, migrants with lower levels had an OR of 14.02 (1.76-111.70), whereas no association was evident in Italians. CONCLUSIONS: Our case-control study within the Piedmont Diabetes Registry showed no association between vitamin D levels at birth and risk of having type 1 diabetes up to 10 years of age, apart from the subgroup of migrant babies, which might have clinical implications if confirmed.

Obestatin levels are associated with C-peptide and antiinsulin antibodies at the onset, whereas unacylated and acylated ghrelin levels are not predictive of long-term metabolic control in children with type 1 diabetes.

CONTEXT AND OBJECTIVE: Ghrelin secretion is altered at the onset and after the start of insulin therapy in children with type 1 diabetes. Contemporary regulation of acylated ghrelin (AG), unacylated ghrelin (UAG), and obestatin (OBST) remains undefined in this disease. It is unknown as to whether they could be good predictors of changes in glucose and metabolic control. DESIGN, SETTING, AND SUBJECTS: This was a longitudinal study conducted in a tertiary care center. AG, UAG, and OBST were measured at baseline and after 2 years of follow-up in 51 children and adolescents with a history of type 1 diabetes extending beyond 1 year. A total of 33 healthy matched subjects were used as controls. RESULTS: Age-, puberty-, and body mass index-adjusted UAG levels were lower (P < .005) and OBST levels were higher (P < .009) in children with type 1 diabetes, with respect to controls. AG levels were similar to controls, but all ratios of the three peptides are altered in diabetic patients. OBST (P < .05) was negatively correlated with C-peptide (P < .05) and insulin antibodies (P < .008) at the onset of diabetes. In diabetic patients, baseline AG and UAG levels were negatively correlated with insulin dosage in the short and long term (P < .001). AG, but not OBST, was positively correlated with C-peptide levels 2 years after diagnosis (P < .05). Overall, the peptides were not predictive of glucose and metabolic control. CONCLUSIONS: UAG, AG, OBST, and their ratios are differently regulated in children with type 1 diabetes, suggesting a role in the metabolic balance of the disease, with insulin a likely regulator of AG and UAG. The peptides do not appear to be good long-term predictors of glucose control, with further investigations needed to explain whether OBST could be a precocious predictor of islet dysfunction.

Increasing burden, younger age at onset and worst metabolic control in migrant than in Italian children with type 1 diabetes: an emerging problem in pediatric clinics.

To assess burden and clinical features of type 1 diabetes in migrant with respect to Italian children. Prevalent children with type 1 diabetes were identified through a multicenter study, including 46 pediatric outpatients diabetic clinics. A nested case-control study was also performed, comparing features at diabetes onset and after 1 year of insulin treatment in 84 migrants and 75 Italian children with onset in 2011, matched for age and sex. Out of 7,812 children cared for by pediatric diabetologists, 761 (10%) were migrant and 548 of them were born in Italy. Age at diagnosis was lower in migrants born in Italy (5.1 years, interquartile range (IQR) 2.2-7.7) than in those born in their original countries (7.8 years, IQR 5.3-10.3) and in Italians (9.8 years, IQR 5.9-13.0, p < 0.001). At diabetes onset, migrants had lower frequencies of positivities of markers of ß-cell autoimmunity (96 vs. 99.5%, p < 0.01), higher values of weight loss (11 vs. 7%, p < 0.01), HbA1c (70 vs. 58 mmol/mol, p < 0.001), and insulin requirement (0.70 ± 0.03 vs. 0.63 ± 0.10 UI/kg/die, p = 0.05) and lower levels of 25-OH vitamin D3 (15.0 ± 2.8 vs. 20.8 ± 1.3, p = 0.03). Moreover, they experienced higher frequencies of hospitalizations during the first year of disease (19.2 vs. 2.7%, p < 0.001). Burden of type 1 diabetes in migrant children is increasing in Italy, with younger age at onset and different clinical features than in Italian children. Higher hospitalization rates and poorer glycemic control over the first year underline that approach to diabetes care in migrants needs to be improved.

Vitamin D status in cord blood and newborns: ethnic differences.

BACKGROUND: A deficiency in vitamin D (25OHD) is common throughout the world in both adults and children, being related to skin pigmentation, sun exposure, dietary intake and obesity. Limited data are available for the neonatal age. The aim of the study is to understand the differences in 25OHD levels with respect to skin colour and ethnicity in newborns. METHODS: We randomly enrolled 62 neonates, born at term and appropriate for gestational age. Thirty two were born from Italian mothers with fair skin (FS) and 30 from non-Caucasian mothers (North African, African, Asian and Latin American): 10 with light olive/light brown (LOB) and 20 with medium brown/black skin (MBB). Vitamin D was measured in the cord blood at birth and in neonatal serum during metabolic screening. RESULTS: 25OHD levels were (mean ± SD) 21.4 ± 11 ng/ml in cord blood and 14.9 ± 7 ng/ml in serum after birth. 25OHD values were higher in cord blood (p < 0.01) and neonatal serum (p < 0.001) in subjects supplemented with Vitamin D. Newborn FS showed higher vitamin D levels in cord blood when compared to LOB and MBB (p < 0.01), and higher levels in neonatal serum when compared to LOB (p < 0.01). In cord blood, 25OHD levels were higher in Italian newborns than in North African (p < 0.004) and African (p < 0.01). In neonatal serum, 25OHD levels were higher in Italian infants only when compared with North African infants (p < 0.03). CONCLUSIONS: The present study shows a high prevalence of vitamin D insufficiency and deficiency in newborns with significant differences observed to be due to ethnicity, skin colour and maternal supplementation during the pregnancy.

Seven mutations in the human insulin gene linked to permanent neonatal/infancy-onset diabetes mellitus.

Permanent neonatal diabetes mellitus (PNDM) is a rare disorder usually presenting within 6 months of birth. Although several genes have been linked to this disorder, in almost half the cases documented in Italy, the genetic cause remains unknown. Because the Akita mouse bearing a mutation in the Ins2 gene exhibits PNDM associated with pancreatic beta cell apoptosis, we sequenced the human insulin gene in PNDM subjects with unidentified mutations. We discovered 7 heterozygous mutations in 10 unrelated probands. In 8 of these patients, insulin secretion was detectable at diabetes onset, but rapidly declined over time. When these mutant proinsulins were expressed in HEK293 cells, we observed defects in insulin protein folding and secretion. In these experiments, expression of the mutant proinsulins was also associated with increased Grp78 protein expression and XBP1 mRNA splicing, 2 markers of endoplasmic reticulum stress, and with increased apoptosis. Similarly transfected INS-1E insulinoma cells had diminished viability compared with those expressing WT proinsulin. In conclusion, we find that mutations in the insulin gene that promote proinsulin misfolding may cause PNDM.

Variations of the perforin gene in patients with type 1 diabetes.

OBJECTIVE: Perforin plays a key role in cell-mediated cytotoxicity. Mutations of its gene, PRF1, cause familial hemophagocytic lymphohistiocytosis but have also been associated with lymphomas and the autoimmune/lymphoproliferative syndrome. The aim of this work was to investigate the role of PRF1 variations in type 1 diabetes. RESEARCH DESIGN AND METHODS: We typed for the N252S and A91V variations in an initial population of 352 type 1 diabetic patients and 816 control subjects and a second population of 365 patients and 964 control subjects. Moreover, we sequenced the coding sequence and intron-exons boundaries in 200 patients and 300 control subjects. RESULTS: In both cohorts, allelic frequency of N252S was significantly higher in patients than in control subjects (combined cohorts: 1.5 vs. 0.4%; odds ratio 6.68 [95% CI 1.83-7.48]). Sequencing of the entire coding region detected one novel mutation in one patient, causing a P477A amino acid change not detected in 199 patients and 300 control subjects. Typing for HLA-DQA1 and DQB1 alleles showed that type 1 diabetes-predisposing DQ alpha/DQ beta heterodimers were less frequent in patients carrying N252S or P477A than in those carrying wild-type PRF1. We previously found that natural killer (NK) activity is not decreased in most N252S heterozygotes, but we detected one whose NK activity was normal at the age of 12 but strikingly low in early childhood. Here, we discovered that NK function was low in three heterozygotes in early childhood, one homozygous adult, and in the subject carrying P477A. CONCLUSIONS: These data suggest that N252S and possibly other PRF1 variations are susceptibility factors for type 1 diabetes development.

The G53D mutation in Kir6.2 (KCNJ11) is associated with neonatal diabetes and motor dysfunction in adulthood that is improved with sulfonylurea therapy.

CONTEXT: Mutations in the Kir6.2 subunit (KCNJ11) of the ATP-sensitive potassium channel (KATP) underlie neonatal diabetes mellitus. In severe cases, Kir6.2 mutations underlie developmental delay, epilepsy, and neonatal diabetes (DEND). All Kir6.2 mutations examined decrease the ATP inhibition of KATP, which is predicted to suppress electrical activity in neurons (peripheral and central), muscle, and pancreas. Inhibitory sulfonylureas (SUs) have been used successfully to treat diabetes in patients with activating Kir6.2 mutations. There are two reports of improved neurological features in SU-treated DEND patients but no report of such improvement in adulthood. OBJECTIVE: The objective of the study was to determine the molecular basis of intermediate DEND in a 27-yr-old patient with a KCNJ11 mutation (G53D) and the patient's response to SU therapy. DESIGN: The G53D patient was transferred from insulin to gliclazide and then to glibenclamide over a 160-d period. Motor function was assessed throughout. Electrophysiology assessed the effect of the G53D mutation on KATP activity. RESULTS: The G53D patient demonstrated improved glycemic control and motor coordination with SU treatment, although glibenclamide was more effective than gliclazide. Reconstituted G53D channels exhibit reduced ATP sensitivity, which is predicted to suppress electrical activity in vivo. G53D channels coexpressed with SUR1 (the pancreatic and neuronal isoform) exhibit high-affinity block by gliclazide but are insensitive to block when coexpressed with SUR2A (the skeletal muscle isoform). High-affinity block by glibenclamide is present in G53D channels coexpressed with either SUR1 or SUR2A. CONCLUSION: The results demonstrate that SUs can resolve motor dysfunction in an adult with intermediate DEND and that this improvement is due to inhibition of the neuronal but not skeletal muscle KATP.