The frequent UCP2 -866G>A polymorphism protects against insulin resistance and is associated with obesity: a study of obesity and related metabolic traits among 17 636 Danes.

CONTEXT: Uncoupling protein 2 (UCP2) is involved in regulating ATP synthesis, generation of reactive oxygen species and glucose-stimulated insulin secretion in ß-cells. Polymorphisms in UCP2 may be associated with obesity and type 2 diabetes mellitus. OBJECTIVE: To determine the influence of a functional UCP2 promoter polymorphism (-866G>A, rs659366) on obesity, type 2 diabetes and intermediary metabolic traits. Furthermore, to include these and previously published data in a meta-analysis of this variant with respect to its impact on obesity and type 2 diabetes. DESIGN: We genotyped UCP2 rs659366 in a total of 17 636 Danish individuals and established case-control studies of obese and non-obese subjects and of type 2 diabetic and glucose-tolerant subjects. Meta-analyses were made in own data set and in publicly available data sets. Quantitative traits relevant for obesity and type 2 diabetes were analysed within separate study populations. RESULTS: We found no consistent associations between the UCP2 -866G-allele and obesity or type 2 diabetes. Yet, a meta-analysis of data from 12 984 subjects showed an association with obesity (GA vs GG odds ratio (OR) (95% confidence interval (CI)): 0.894(0.826-0.968) P=0.00562, and AA vs GG OR(95% CI): 0.892(0.800-0.996), P=0.0415. Moreover, a meta-analysis for type 2 diabetes of 15 107 individuals showed no association. The -866G-allele was associated with elevated fasting serum insulin levels (P=0.002) and HOMA insulin resistance index (P=0.0007). Insulin sensitivity measured during intravenous glucose tolerance test in young Caucasian subjects (n=377) was decreased in carriers of the GG genotype (P=0.05). CONCLUSIONS: The UCP2 -866G-allele is associated with decreased insulin sensitivity in Danish subjects and is associated with obesity in a combined meta-analysis.

A variant in the G6PC2/ABCB11 locus is associated with increased fasting plasma glucose, increased basal hepatic glucose production and increased insulin release after oral and intravenous glucose loads.

AIMS/HYPOTHESIS: An association between elevated fasting plasma glucose and the common rs560887 G allele in the G6PC2/ABCB11 locus has been reported. In Danes we aimed to examine rs560887 in relation to plasma glucose and serum insulin responses following oral and i.v. glucose loads and in relation to hepatic glucose production during a hyperinsulinaemic-euglycaemic clamp. Furthermore, we examined rs560887 for association with impaired fasting glycaemia (IFG), impaired glucose tolerance (IGT), type 2 diabetes and components of the metabolic syndrome. METHODS: rs560887 was genotyped in the Inter99 cohort (n = 5,899), in 366 young, healthy Danes, in non-diabetic relatives of type 2 diabetic patients (n = 196), and in young and elderly twins (n = 159). Participants underwent an OGTT, an IVGTT or a 2 h hyperinsulinaemic-euglycaemic clamp. RESULTS: The rs560887 G allele associated with elevated fasting plasma glucose (p = 2 x 10(-14)) but not with plasma glucose levels at 30 min (p = 0.9) or 120 min (p = 0.9) during an OGTT. G allele carriers had elevated levels of serum insulin at 30 min during an OGTT (p = 1 x 10(-4)) and relatives of type 2 diabetes patients carrying the G allele had an increased acute insulin response (p = 4 x 10(-4)) during an IVGTT. Among elderly twins, G allele carriers had higher basal hepatic glucose production (p = 0.04). Finally, the G allele associated with the risk of having IFG (OR 1.26, 95% CI 1.08-1.47, p = 0.002), but not with IGT (OR 0.94, 95% CI 0.82-1.08, p = 0.4) or type 2 diabetes (OR 0.93, 95% CI 0.84-1.04, p = 0.2). CONCLUSIONS/INTERPRETATION: The common rs560887 G allele in the G6PC2/ABCB11 locus is associated with increased fasting glycaemia and increased risk of IFG, associations that may be partly related to an increased basal hepatic glucose production rate.

Insulin sensitivity index, acute insulin response, and glucose effectiveness in a population-based sample of 380 young healthy Caucasians. Analysis of the impact of gender, body fat, physical fitness, and life-style factors.

BACKGROUND: Insulin sensitivity and insulin secretion are traits that are both genetically and environmentally determined. AIM: The aim of this study was to describe the distribution of the insulin sensitivity index (Si), the acute insulin response, and glucose effectiveness (Sg) in young healthy Caucasians and to estimate the relative impact of anthropometric and environmental determinants on these variables. METHODS: The material included 380 unrelated Caucasian subjects (18-32 yr) with measurement of Si, Sg and insulin secretion during a combined intravenous glucose (0.3 grams/kg body weight) and tolbutamide (3 mg/kg body weight) tolerance test. RESULTS: The distributions of Si and acute insulin response were skewed to the right, whereas the distribution of Sg was Gaussian distributed. Sg was 15% higher in women compared with men (P < 0.001). Waist circumference, body mass index, maximal aerobic capacity, and women's use of oral contraceptives were the most important determinants of Si. Approximately one-third of the variation of Si could be explained by these factors. Compared with individuals in the upper four-fifths of the distribution of Si, subjects with Si in the lowest fifth had higher waist circumference, higher blood pressure, lower VO2max, and lower glucose tolerance and fasting dyslipidemia and dysfibrinolysis. Only 10% of the variation in acute insulin response could be explained by measured determinants. CONCLUSION: Estimates of body fat, maximal aerobic capacity, and women's use of oral contraceptives explain about one-third of the variation in Si in a population-based sample of young healthy Caucasians.

Insulin sensitivity and body weight changes in young white carriers of the codon 64 amino acid polymorphism of the beta 3-adrenergic receptor gene.

Recently, a missense mutation replacing tryptophan with arginine at codon 64 of the beta 3-adrenergic receptor gene was shown to be associated with insulin resistance in nondiabetic subjects and to an earlier onset of NIDDM in Pima Indians. We studied whether the codon 64 amino acid polymorphism of the beta 3-adrenergic receptor gene in a cohort of young healthy Danes was associated with high birth weight, accelerated weight gain during childhood and adolescence, present obesity, or impaired insulin sensitivity. The protocol included 380 unrelated white subjects in whom insulin sensitivity and secretion were measured during a combined intravenous glucose and tolbutamide tolerance test. A number of biochemical and anthropometric characteristics were determined for each subject. The subjects were genotyped for the codon 64 polymorphism by applying polymerase chain reaction restriction fragment-length polymorphism screening with the use of endonuclease BstN1. The allelic frequency of the mutated allele was 7% (95% CI: 5-10%), and it was similar in obese and nonobese subjects. The beta 3-adrenergic receptor gene variant was not related to birth weight or weight gain during childhood or adolescence. In its heterozygous form, the gene variant was not associated with an altered insulin sensitivity index (SI) or other features of the insulin resistance syndrome (BMI, blood pressure, fasting serum lipid levels, or fasting serum fibrinolytic variables). Three homozygous carriers of the polymorphism were identified, and each had a significantly higher BMI (27.4 +/- 1.3 vs. 23.5 +/- 3.7 kg/m2 [mean +/- SD]; P = 0.032), lower SI [4.9 +/- 2.9 vs. 15.4 +/- 9.0 10(-5) x (min x pmol/l)-1; P = 0.013], and higher fasting serum C-peptide (730 +/- 155 vs. 471 +/- 158 pmol/l; P = 0.016) than the wild-type carriers. The homozygous carriers also had significantly higher levels of fasting serum triglyceride (P = 0.042) and serum LDL cholesterol (P = 0.013). When adjustments were made for age, sex, BMI, and VO2max in a multiple regression analysis, a significantly negative association was found between homozygosity for the codon 64 variant and the SI (P = 0.009). We conclude that in young healthy Danes, the homozygous form but not the heterozygous form of the codon 64 amino acid polymorphism of the beta 3-adrenergic receptor may be associated with obesity and, independent of BMI, with a low SI. Since only three homozygous carriers were identified among 380 subjects, the results must be interpreted with caution, and studies of larger population samples are needed.

Amino acid polymorphisms in the ATP-regulatable inward rectifier Kir6.2 and their relationships to glucose- and tolbutamide-induced insulin secretion, the insulin sensitivity index, and NIDDM.

Kir6.2 is an inwardly rectifying potassium channel that is expressed in pancreatic beta-cells and cardiac and skeletal muscle. Expressed together with the high-affinity sulphonylurea receptor, it reconstitutes a sulphonylurea- and also ATP-sensitive potassium channel resembling the native beta-cell channel. The objective of this study was to search for mutations in the Kir6.2 gene that might be associated with NIDDM or related to altered insulin secretion, insulin action, or glucose metabolism in healthy subjects. Using polymerase chain reaction-single-strand conformation polymorphism analysis (PCR-SSCP) on genomic DNA from 69 Danish NIDDM patients and 66 matched control subjects, we report the finding of three missense polymorphisms in otherwise conserved codons and three silent polymorphisms in the gene encoding Kir6.2: codon 23 (GAG/AAG), Glu-->Lys; codon 190 (GCT/GCC), Ala-->Ala; codon 267 (CTC/CTG), Leu-->Leu; codon 270 (CTG/GTG), Leu-->Val; codon 337 (ATC/GTC), Ile-->Val; codon 381 (AAG/AAA), Lys-->Lys. The codon 23 and codon 337 amino acid polymorphisms were always coupled. The allelic frequencies of the polymorphisms were similar in NIDDM patients and control subjects. The amino acid polymorphisms were not associated with altered insulin secretion after intravenous glucose or tolbutamide injections or with altered glucose effectiveness in a phenotype study of 346 young healthy subjects. However, carriers of the maximal load of amino acid variants, the compound homozygous codon 23/337 and heterozygous codon 270, had on average a 62% higher insulin sensitivity index (P = 0.006), compared with noncarriers. We conclude that a combination of common Kir6.2 amino acid variants may contribute to the genetic background behind the large variation of the insulin sensitivity index in the general population.

Intermediate expansions of a GAA repeat in the frataxin gene are not associated with type 2 diabetes or altered glucose-induced beta-cell function in Danish Caucasians.

A variable expansion of a GAA repeat is present in the first intron of the frataxin gene, also termed FRDA1 or X25. Long repeat lengths (>66 repeats) are present in patients with Friedreich's ataxia, while an intermediate expansion (10-66 repeats) has recently been reported to be highly associated with type 2 diabetes. Using a polymerase chain reaction-based assay, we found that 32.4% (95%CI 29.9-34.9) of 636 Danish Caucasian type 2 diabetic patients were carriers of an intermediate expansion, whereas the frequency was 30.4% (26.4-34.4) among 224 matched glucose-tolerant control subjects (P = 0.6). In the control subjects, the values of serum insulin and C-peptide responses during an oral glucose tolerance test were similar between the 69 carriers and 155 noncarriers. Furthermore, we investigated a possible relationship between expansions of the FRDA1 gene and glucose-induced beta-cell function in 338 young Caucasians (33.7% [30.1-37.3] carriers) and in 215 glucose-tolerant subjects (31.0% [26.6-35.4] carriers) with a type 2 diabetic parent. In neither population did the carriers differ from noncarriers according to values of fasting plasma glucose, serum insulin, or C-peptide, acute serum insulin, or C-peptide responses after intravenous glucose. In conclusion, intermediate expansion of the frataxin trinucleotide repeat is not associated with type 2 diabetes or altered glucose-induced insulin secretion in Danish Caucasians.

Identification of four amino acid substitutions in hexokinase II and studies of relationships to NIDDM, glucose effectiveness, and insulin sensitivity.

Human hexokinase (HK) II, a glucose phosphorylating enzyme in muscle tissue, plays a central role in glucose metabolism. Since reduced insulin-stimulated glucose uptake and reduced glucose-6-phosphate content in muscle have been demonstrated in pre-non-insulin-dependent diabetes mellitus (pre-NIDDM) and NIDDM subjects, we have examined the coding region of the HKII gene in NIDDM patients to determine whether these patients show genetic polymorphisms that are associated with or contribute to the disease. Single-strand conformational polymorphism analysis and nucleotide sequencing were initially performed on the entire coding region of the HKII gene of 38 insulin-resistant NIDDM patients and 5 healthy control subjects. This analysis revealed four missense mutations at codons 142 (Gln to His), 148 (Leu to Phe), 497 (Arg to Gln), and 844 (Arg to Lys) and an additional six exon polymorphisms that did not predict any change in amino acid composition of the protein. One homozygous and nine heterozygous carriers of the codon 142 mutation were found among the NIDDM patients. The mutations at codons 148, 497, and 844 were each found in one diabetic subject and only on one allele. There were no carriers of compound heterozygous mutations. A subsequent study of 301 patients with NIDDM and 151 healthy control subjects revealed no additional mutations at codons 148, 497, or 844. The total frequency of the mutated allele at codon 142 was 18.9% among the control subjects and 17.0% among the NIDDM patients (chi 2 = 0.56, P = 0.45).(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of a common amino acid polymorphism in the p85alpha regulatory subunit of phosphatidylinositol 3-kinase: effects on glucose disappearance constant, glucose effectiveness, and the insulin sensitivity index.

Phosphatidylinositol 3-kinase (PI3-K) may regulate the basal plasma membrane glucose transporter recycling and the organization of the transporter intracellular pool in addition to being an insulin signal for translocation of glucose transporters to the plasma membrane. The objectives of the present study were to examine for genetic variability in the human regulatory p85alpha subunit of PI3-K, to look for an association between gene variants and NIDDM in a case-control study, and to relate identified variability to potential changes in whole-body insulin sensitivity and glucose turnover in a phenotype study. Single-strand conformational polymorphism and heteroduplex analysis of the coding region of the regulatory p85alpha subunit in cDNA isolated from human muscle tissue from 70 insulin-resistant NIDDM patients and 12 control subjects revealed three silent polymorphisms and a missense mutation at nucleotide position 1020 (G-->A), changing a Met to Ile at codon 326. Using allele-specific oligohybridization, we found a similar allelic frequency of the codon 326Met-->Ile variant in 404 NIDDM patients (0.15 [95% CI 0.13-0.17]) and 224 matched glucose tolerant control subjects (0.16 [0.13-0.19]). In a random sample of 380 unrelated healthy young Caucasians aged 18-32 years, in whom we have performed a tolbutamide modified intravenous glucose tolerance test, we identified 263 wildtype subjects, 109 heterozygous subjects, and 8 subjects homozygous for the codon 326 variant (allelic frequency = 0.16 [0.13-0.19]). No difference in glucose disappearance constant (KG), insulin sensitivity index (SI), and glucose effectiveness (SG) was observed between wildtype and heterozygous subjects. However, compared with the combined values for wildtype and heterozygous carriers, KG was reduced by 40% (P = 0.004) and SG by 23% (P = 0.03) in homozygous carriers of the p85alpha variant. Moreover, in homozygous carriers, a 32% reduction was found in SI (P = 0.08). In conclusion, a codon 326Met-->Ile variant in the gene encoding the PI3-K p85alpha regulatory subunit is found in 31% of a random sample of young healthy Caucasians. About 2% of the subjects in this population carry the gene variant in its homozygous form, and these carriers are characterized by significant reductions in whole-body glucose effectiveness and intravenous glucose disappearance constant. In itself, the gene variant does not confer an increased risk of diabetes.

A prevalent amino acid polymorphism at codon 98 in the hepatocyte nuclear factor-1alpha gene is associated with reduced serum C-peptide and insulin responses to an oral glucose challenge.

Mutations in the hepatocyte nuclear factor-1alpha (HNF-1alpha) gene cause the type 3 form of maturity-onset diabetes of the young (MODY3), which is characterized by a severe impairment of insulin secretion. In addition to disease-associated mutations, three common amino acid polymorphisms have been identified in the HNF-1alpha gene: Ile/Leu27, Ala/Val 98, and Ser/Asn487. We have addressed the question of whether these variants of the HNF-1alpha gene are associated with altered glucose-induced C-peptide and insulin responses or late-onset NIDDM. Among 245 NIDDM patients, the allelic frequency of the Val 98 variant was 3.7% (95% CI 2.0-5.4%) vs. 4.4% (2.6-6.2%) among 240 glucose tolerant control subjects (NS). Studies of genotype-phenotype interactions in 240 middle-aged control subjects showed, however, that heterozygous subjects (i.e., genotype Ala/Val 98) had an 18% decrease in 30-min serum C-peptide level (P = 0.004) as well as a 23% decrease in 30-min serum insulin level (P = 0.03) during an oral glucose tolerance test. One Val 98 homozygote subject had a more severe reduction in stimulated insulin and C-peptide levels. The impact of the homozygous carrier status was similar in a study of 377 healthy young subjects. In contrast, the Ile/Leu27 and Ser/Asn487 polymorphisms were not associated with altered C-peptide and insulin release or NIDDM. In conclusion, 8% of white subjects of Danish ancestry are heterozygous for the Ala/Val 98 polymorphism in the HNF-1alpha gene, which in middle-aged subjects is associated with a approximately 20% reduction in serum C-peptide and insulin responses 30 min after an oral glucose challenge. Val 98 homozygotes may exhibit a more severe defect in the early glucose-induced insulin response.

Decreased tolbutamide-stimulated insulin secretion in healthy subjects with sequence variants in the high-affinity sulfonylurea receptor gene.

The high-affinity sulfonylurea receptor (SUR1) is, as a subunit of the ATP-sensitive potassium channel, an important regulator of insulin secretion in the pancreatic beta-cell. The aim of this study was to examine if genetic variability of the SUR1 gene was associated with NIDDM or altered pancreatic beta-cell function. Mutational analysis of all the 39 SUR1 exons, including intron-exon boundaries, in 63 NIDDM patients revealed two missense variants, five silent variants in the coding region, and four intron variants. The two missense variants (Asp673Asn and Ser1369Ala) and two sequence variants (ACC-->ACT, Thr759Thr and a c-->t intron variant in position -3 of the exon 16 splice acceptor site) were examined for association with NIDDM and for a possible influence on insulin and C-peptide secretion after intravenous glucose and tolbutamide loads in a random sample of unrelated, healthy, young Danish Caucasians. The Asp673Asn variant in exon 14 was only identified in one NIDDM patient, and the allelic frequency of the Ser1369Ala was similar among 247 control subjects (0.38 [95% CI 0.34-0.42]) and 406 NIDDM patients (0.40 [0.37-0.43]). The allelic frequency of the silent exon 18 Thr775Thr variant was 0.051 (0.035-0.067) in NIDDM patients (n=392) and 0.027 (0.013-0.041) in control subjects (n=246; chi2=4.99, P=0.03). The allelic frequency of the intron variant was similar among NIDDM patients (0.45 [0.42-0.48]) and control subjects (0.44 [0.40-0.48]). Of 386 NIDDM patients, 17 had the combined genotype exon 18 C/T and intron -3c/-3t (0.044 [0.024-0.064]), whereas 3 of 243 control subjects had the same combined genotype (0.012 [0-0.026]; chi2=4.87, P=0.03; odds ratio: 3.69 [1.07-12.71]). Of 380 unrelated, healthy, young Danish Caucasians, 10 (0.026 [0.010-0.042]) had the combined at-risk genotype. These subjects had, on average, a 50% reduction in serum C-peptide and a 40% reduction in serum insulin responses upon tolbutamide injection (P=0.002 and P=0.05, respectively) but normal serum C-peptide and insulin responses upon glucose injection. In conclusion, a silent polymorphism in exon 18 of the SUR1 gene is associated with NIDDM in a Danish Caucasian population. In combination with an intron variant, the association is higher, and young, healthy carriers of the intragenic combination have reduced serum C-peptide and insulin responses to a tolbutamide load.

Discovery of a Met300Val variant in Shc and studies of its relationship to birth weight and length, impaired insulin secretion, insulin resistance, and type 2 diabetes mellitus.

The Shc adaptor proteins corresponding to the 46-, 52-, and 66-kDa isoforms are key transducers of growth promotion and gene expression, which are being phosphorylated by all known receptor tyrosine kinases after stimulation by growth factors such as insulin and insulin-like growth factor I. Several studies have demonstrated a relationship between intrauterine growth retardation and impaired glucose tolerance or type 2 diabetes later in life. It is unclear whether this finding is partially explained by genetic factors. In this context, abnormalities in Shc proteins are considered to be a plausible candidate. Therefore, the aim of this study was to analyze whether genetic variability of the Shc isoforms causes a decrease in cell growth and cell differentiation that could be manifested by a decrease in birth weight and length, impaired acute insulin secretion after i.v. glucose, insulin resistance, and eventually a higher prevalence of type 2 diabetes. By single strand conformation polymorphism-heteroduplex analysis of 70 patients with diabetes mellitus and subsequent nucleotide sequencing of identified single strand conformation polymorphism variant, we discovered a Met300Val substitution of the 52-kDa isoform. The amino acid variant was predicted to be present in all 3 isoforms of Shc. In a genotype-phenotype study of 360 young healthy subjects, the allelic frequency of the codon 300 polymorphism was 4.2%. In this cohort, no significant differences could be shown between carriers and noncarriers in birth weight and length, the acute insulin response to i.v. glucose, or the insulin sensitivity index, as estimated from an i.v. glucose tolerance test. In an association study of 313 type 2 diabetic patients and 226 matched glucose-tolerant subjects, there was no significant difference in allelic frequency of the Shc variant (5.1% in diabetic patients vs. 3.1% in control subjects; P = 0.11). In conclusion, by itself the Met300Val polymorphism of Shc has no major impact on birth weight and length, insulin sensitivity index, acute glucose-induced insulin secretion, or prevalence of random type 2 diabetes mellitus.

Studies of the impact of a liver glucokinase promoter variant on glucose tolerance and insulin sensitivity index.

Because a frequently occurring nucleotide substitution at position -258 in the liver glucokinase promoter has been reported to be associated with impaired promoter activity, we have examined in Danish Caucasians whether this variant is associated with alterations in glucose tolerance and/or the insulin sensitivity index (Si). Among 246 Danish Caucasian patients with noninsulin-dependent diabetes mellitus, the allelic frequency of the -258 promoter variant was 15.2% (95% confidence interval: 12.0-18.4%) vs. 16.5% (13.2-19.8%) among 242 matched control subjects. In the control group, the glucokinase variant was not related to serum insulin or plasma glucose levels before or during an oral glucose tolerance test. Neither was the gene variant among 380 young, healthy subjects associated with altered Si or altered insulin secretion after an i.v. glucose load. We conclude that in Danish Caucasians, the -258 glucokinase promoter variant has no impact on glucose tolerance, whole-body Si, or insulin secretion.

Studies of genetic variability of the uncoupling protein 1 gene in Caucasian subjects with juvenile-onset obesity.

Our objective was to investigate whether genetic variants of the uncoupling protein 1 (UCP1) gene are associated with juvenile-onset obesity or alterations in weight gain and insulin sensitivity in young healthy Caucasians. Single-strand conformation polymorphism and heteroduplex analysis of the coding region of the UCP1 gene was performed in 56 subjects randomly selected at the draft board examination from a cohort of 156 males with juvenile-onset obesity. Association studies of amino acid variants were undertaken in the cohort of males with juvenile-onset obesity, a cohort of 205 randomly selected control males, and a subgroup of this cohort comprising 76 lean subjects. Genetic variants of the coding region as well as a previously described a-->g nucleotide polymorphism of the 5'-flanking region of the UCP1 gene were examined for associations with accelerated weight gain or reduced sensitivity to insulin in a cohort of 380 young healthy Caucasians. The mutational analysis revealed five nucleotide substitutions that changed the sequence of UCP1, Arg/Trp40, Ala/Thr64, Val/Met137, Met/Leu229, and Lys/Asn257 and two nucleotide substitutions in the nontranslated region of exon 1. Among subjects with juvenile-onset obesity, the allelic frequencies of Ala/Thr64 and Met/Leu229 were both 8.2% (95% confidence interval: 5.1-11.3%) vs. 8.8% (6.0-11.6%) and 8.1% (5.3-10.9%), respectively, in the cohort of randomly selected control subjects. Among lean control subjects, the allelic frequencies of the polymorphisms were 8.2% (3.7-12.7%) and 5.6% (1.9-9.3%), respectively. In the cohort of young healthy subjects, measurements of obesity and insulin sensitivity did not differ between carriers of the Ala/Thr64 and Met/Leu229 variants and wild-type carriers. The Val/Met137 and Lys/Asn257 mutations were each found in one subject with juvenile-onset obesity, and the Arg/Trp40 mutation was found in two obese subjects and in one control subject. The allelic frequency of the nucleotide polymorphism of the 5'-flanking region of the UCP1 gene was 25.3% (22.2-28.4%) in the cohort of 380 young Danes. There were no differences in body mass index, fat mass, waist-to-hip ratio, or weight gain during childhood or adolescence between carriers and noncarriers of this nucleotide variant. Although we cannot exclude an effect of the rare mutations in the UCP1 gene on susceptibility to juvenile-onset obesity, genetic variation of the coding region of the UCP1 gene is not a common factor contributing to obesity in Caucasian subjects of Danish ancestry.

The effect of two frequent amino acid variants of the hepatocyte nuclear factor-1alpha gene on estimates of the pancreatic beta-cell function in Caucasian glucose-tolerant first-degree relatives of type 2 diabetic patients.

The objective of the present study was to investigate whether the frequent amino acid polymorphisms, Ile/Leu27 and Ser/Asn487, of the hepatocyte nuclear factor-1alpha gene were associated with alterations in glucose-induced serum C-peptide and serum insulin responses among glucose-tolerant first-degree relatives of type 2 diabetic patients. The study comprised 2 independent Danish cohorts. Among 74 unrelated type 2 diabetic relatives, 12 homozygous carriers of the Ile/Leu27 polymorphism had a 32% decrease in the 30-min serum C-peptide level (P = 0.01), as well as a 39% decrease in the 30-min serum insulin level (P = 0.02) during an oral glucose tolerance test. Ten homozygous carriers of the Ile/Leu27 variant did, however, not differ from wild-type carriers, with respect to the acute circulating insulin and serum C-peptide responses during an i.v. glucose tolerance test in the same study cohort. In a larger (more than 3-fold) study group of 230 glucose tolerant offspring of 62 type 2 diabetic probands, 33 homozygous carriers of the Ile/Leu27 variant did not differ, with respect to either serum insulin and serum C-peptide levels during an oral glucose tolerance test or acute serum insulin and serum C-peptide responses during an i.v. glucose tolerance test. We therefore consider the former positive finding as a statistical type I error. There were no differences in the above mentioned variables between carriers of the Ser/Asn487 polymorphism and wild-type carriers within any of the 2 study populations. Nor did carriers of combined genotypes, i.e. carriers of both the Ile/Leu27 and the Ser/Asn487 variants, show any associations with the examined variables. In conclusion, the Ile/Leu27 and Ser/ Asn487 polymorphisms of the hepatocyte nuclear factor-1alpha gene have apparently no major impact on the pancreatic beta-cell function, after an oral and i.v. glucose challenge, in Caucasian first-degree relatives of type 2 diabetic patients.

The importance of adrenaline, insulin and insulin sensitivity as determinants for blood pressure in young Danes.

OBJECTIVE: To study the influence of the adrenergic system, fasting serum insulin level and insulin sensitivity on systolic (SBP) and diastolic blood pressure (DBP) in young individuals. DESIGN AND METHODS: In a population survey we measured SBP and DBP (using the London School of Hygiene sphygmomanometer) and fasting levels of serum catecholamines, serum insulin and insulin sensitivity in 383 randomly recruited subjects (mean age 25.0 years) of both sexes. Insulin sensitivity was estimated from a combined intravenous glucose and tolbutamide tolerance test and calculated using Bergman's minimal model. Confounders were body mass index, waist:hip ratio, maximal aerobic capacity, age, sex, and consumptions of tobacco and alcohol. RESULTS: In a multiple regression analysis including the above factors, the most important determinant of SBP, after sex, was the plasma adrenaline level (partial correlation coefficient, rp = 0.23, P < 0.01). No significant association was found between plasma noradrenaline level and SBP. A significant association was found between plasma adrenaline level and DBP in females only (rp = 0.15, P < 0.05). Overall, the plasma adrenaline level was more important than the plasma noradrenaline level. Fasting serum insulin level and insulin sensitivity were each significantly correlated with both SBP and DBP in univariate analyses, but not in a multiple regression analysis. A family history of hypertension was associated with higher SBP level, body mass index and fasting serum insulin level, and with lower insulin sensitivity, but with no difference in circulating plasma adrenaline or noradrenaline compared with individuals without a family history. In a multiple regression analysis with the above confounders, no significant association between SBP and plasma adrenaline level could be found in either sex for subjects with a family history of hypertension. Both male (rp = 0.41, P < 0.001) and female (rp = 0.18, P < 0.05) subjects with no history of family hypertension had a significant association between SBP and plasma adrenaline level in a multiple regression analysis. CONCLUSION: In young healthy Caucasians adrenergic activity is an important determinant for SBP. The importance of fasting serum insulin level and insulin sensitivity on blood pressure level is minor when confounders are considered.

Analysis of the relationship between fasting serum uric acid and the insulin sensitivity index in a population-based sample of 380 young healthy Caucasians.

AIM: To determine whether fasting serum uric acid is associated with the insulin sensitivity index or with other anthropometric, metabolic or environmental features of the insulin resistance syndrome in a population-based sample of young healthy Caucasians. METHODS: The protocol included 380 unrelated Caucasian subjects (age 18-32 years) who had their insulin sensitivity index and glucose effectiveness measured during a combined intravenous glucose (0.3 g/kg body weight) and tolbutamide (3 mg/kg body weight) tolerance test. A number of anthropometric and biochemical tests, including the level of fasting serum uric acid, were carried out. RESULTS: In univariate analyses the concentration of fasting serum uric acid was negatively correlated to the insulin sensitivity index in both men (r2 = -0.25, P = 0.001) and women (r2 = -0.25, P < 0.001). In multivariate analysis controlling for age, gender, body mass index, waist to hip ratio, maximal aerobic capacity, fasting serum triglyceride and creatinine, daily intake of alcohol, smoking, use of oral contraceptives, and disposition for non-insulin dependent diabetes mellitus, the insulin sensitivity index was not significantly associated with fasting serum uric acid. However, 51% of the variation in the fasting serum uric acid level could be explained, and fasting serum triglyceride was the most important determinant of fasting serum uric acid. CONCLUSION: The major determinant of the fasting serum uric acid level in young healthy Caucasians is the fasting concentration of serum triglyceride, which has been shown to be a biochemical feature of the insulin resistance syndrome. Thus, hyperuricaemia appears to be an indirect part of the insulin resistance syndrome through its association with fasting hypertriglyceridaemia.

Analysis of the relationship between fasting serum leptin levels and estimates of beta-cell function and insulin sensitivity in a population sample of 380 healthy young Caucasians.

OBJECTIVE: Circulating leptin levels correlate positively with the degree of obesity and prolonged hyperinsulinaemia increases serum leptin levels. Moreover, insulin secreting beta-cells express functional leptin receptors indicating a functional relationship between leptin and insulin. The aim of this study was to examine the relationship between fasting serum leptin levels and measures of insulin sensitivity and beta-cell function in a population-based sample of 380 young healthy Caucasians. DESIGN AND METHODS: Multiple regression analysis was employed to analyse the relationship between fasting serum leptin levels and levels of fasting serum insulin, insulin sensitivity index and acute insulin response (AIR) in a population-based study of 380 young healthy Caucasians who underwent a combined intravenous glucose and tolbutamide tolerance test. RESULTS AND CONCLUSION: Serum leptin levels were positively correlated to measures of adiposity and were 3.2 times higher in women than in men (P<0.00001). In multiple regression analyses adjusting for age, percentage body fat, waist circumference and maximal aerobic capacity, a significant positive correlation was observed between the fasting serum leptin concentrations and both fasting serum insulin levels (P<0.0001) and AIR (P = 0.014) for women. No significant interrelation of these variables was found in men. However, for both genders a significant negative correlation was observed between fasting serum leptin levels and measures of insulin sensitivity index (P = 0.007).

Lewis phenotypes and the insulin resistance syndrome in young healthy white men and women.

An increased risk of ischemic heart disease in men with the Lewis blood group phenotype Le(a-b-) has been reported. It has been suggested that the Le(a-b-) phenotype is a genetic marker of the insulin resistance syndrome. To examine whether Le(a-b-) confers the insulin resistance syndrome, we studied a random sample of unrelated healthy young white men and women living in Copenhagen (n = 380, 18 to 32 years). All individuals had their insulin sensitivity estimated using Bergman's minimal model (intravenous glucose in combination with tolbutamide) and systolic blood pressure (SBP) was measured with a London School of Hygiene Sphygmomanometer. A number of anthropometric measurements including body mass index (BMI, kilograms/meters squared) and biochemical characteristics were performed. The Lewis blood group typing was carried out on erythrocytes. Twenty-one men had the Le(a-b-) phenotype. Compared to all other men (N = 165), the Le(a-b-) men had a significantly higher SBP (6 mm Hg, P = .0024). They also had higher values of BMI (8%, P = .016), total body fat mass (25%, P = .015), fasting values of serum insulin (32%, P = .006), serum C-peptide (20%, P = .029), and plasma glucose (8%, P = .003). The fasting values of serum lipids, plasminogen activator inhibitor (PAI-1) activity, tissue plasminogen activator (t-PA) antigen, and insulin sensitivity did not differ between Le(a-b-) men and men with other Lewis phenotypes. Altogether 194 women participated in the study of which 21 women had the Le(a-b-) phenotype. Except for a lower PAI-1 activity (45%, P = .044), no values differed between Le(a-b-) women and women with other Lewis phenotypes. The women were also stratified according to use of oral contraceptives. Le(a-b-) women using oral contraceptives (N = 8) had a significantly lower plasma level of fasting PAI-1 activity (P = .029) and t-PA antigen (P = .004) compared to women using oral contraceptives without the Le(a-b-) phenotype (N = 42). Our data support the hypothesis that Le(a-b-) men exhibit features of the insulin resistance syndrome, including higher levels of BMI, SBP, and fasting levels of serum insulin and plasma glucose. In young women no signs of the insulin resistance syndrome were found in subjects with the Le(a-b-) phenotype.

[Smoking as social heritage. Children whose mothers are smokers are more likely to become smokers as adults]. / Rygning som social arv. Børn, hvis mor er ryger, har øget risiko for at blive rygere som voksne.

Effective prevention of smoking depends on the identification of factors that determine smoking onset. We examined the influence of family factors during childhood (household income, parent education and smoking behaviour) on the subsequent risk of smoking in young adults. In 1979, 1300 children aged 6-18 years, whose parents were randomly selected for participation in the Copenhagen City Heart Study were invited to a health examination. Information about health and smoking behaviour was obtained from 73% of the children. A random sample of 579 of the children were invited to a follow-up examination 13 years later. Four hundred and eighty-six (84%) participated in the follow-up. The influence of household income, parent smoking behaviour and education on the child's risk of becoming a smoker in young adulthood was estimated. Household income and parent education did not significantly affect the risk of adult smoking. Maternal smoking during childhood increased the risk in comparison with the mother being a non-smoker (Adjusted Odds Ratio 1.95 (95% CI 1.07-3.58). Maternal smoking during childhood increases children's risk of becoming young adult smokers, independent of age and smoking behaviour in childhood, gender and social background. In Denmark 28% of smoking in young adults could be attributed to maternal smoking.