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OBJECTIVE--To examine the associations between common variations in the IL6R gene and circulating interleukin (IL)-6 levels and diabetes risk. RESEARCH DESIGN AND METHODS--We determined 10 linkage disequilibrium (LD)-tagging single nucleotide polymorphisms (SNPs) (SNP1 to SNP10) for the IL6R gene in a nested case-control study of 672 diabetic and 1,058 healthy European Caucasian women (IL-6 levels were measured in a subgroup of 1,348 women). RESULTS--In both control and diabetic patients, polymorphisms within an LD block spanning ∼42 kb were significantly associated with plasma IL-6 levels. A missense variant SNP7 in exon 9 (rs8192284, Asp358Ala) showed the strongest association (P = 0.0005 in control and P = 0.004 in case subjects). The corresponding false-discovery rates, which accounts for multiple testing, were 0.008 and 0.02, respectively. We inferred five common haplotypes to capture 94% allele variance of the LD block using SNP5, -7, -8, -9, and -10. Compared with the most common haplotype 12111 (one codes the common and two codes the minor alleles), haplotypes 11211 [difference in log(IL-6) = -0.11 (95% CI -0.23 to -0.01); P = 0.01] and 21122 (-0.15 [-0.27 to -0.03]; P = 0.01) were associated with significantly lower IL-6 levels (global test, P = 0.01). However, IL6R genotypes were not significantly associated with the risk of type 2 diabetes. CONCLUSIONS--IL6R genetic variations, especially SNP7 (rs8192284, Asp358Ala), were significantly associated with plasma IL-6 levels but not with diabetes risk in women. The strong associations between IL6R genetic variability and IL-6 concentrations deserve further investigation. Diabetes 56: 3075-3081, 2007 [ABSTRACT FROM AUTHOR]

OBJECTIVE -- To investigate the association between genetic variation in the adipocyte protein perilipin (PLIN) and insulin resistance in an Asian population as well as to examine their modulation by macronutrient intake. RESEARCH DESIGN AND METHODS -- A nationally representative sample (Chinese, Malays, and Indians) was selected in the Singapore National Health Survey following the World Health Organization-recommended model for field surveys of diabetes. A total of 1,909 men and 2,198 women (aged 18-69 years) were studied. Genetic (PLIN 11482G→A and 14995A→T), lifestyle, clinical, and biochemical data were obtained. Homeostasis model assessment of insulin resistance (HOMA-IR) was used to evaluate insulin resistance. Diet was measured by a validated food frequency questionnaire in one of every two subjects. RESULTS -- We did not find a significant between-genotype difference in insulin resistance measures. However, in women we found statistically significant gene-diet interactions (recessive model) between PLIN 11482G→A/14995A→T polymorphisms (in high linkage disequilibrium) and saturated fatty acids (SFAs; P = 0.003/0.005) and carbohydrate (P = 0.004/0.012) in determining HOMA-IR. These interactions were in opposite directions and were more significant for 11482G→A, considered the tag polymorphism. Thus, women in the highest SFA tertile (11.8-19%) had higher HOMA-IR (48% increase; P trend = 0.006) than women in the lowest (3.1-9.4%) only if they were homozygotes for the PLIN minor allele. Conversely, HOMA-IR decreased (-24%; P trend = 0.046) as carbohydrate intake increased. These effects were stronger when SFAs and carbohydrate were combined as an SFA-to-carbohydrate ratio. Moreover, this gene-diet interaction was homogeneously found across the three ethnic groups. CONCLUSIONS -- PLIN 11482G→A/14995A→T polymorphisms modulate the association between SFAs/carbohydrate in diet and insulin resistance in Asian women. [ABSTRACT FROM AUTHOR]

Little is known about the genetic influence on BMI trajectory throughout adulthood. We created a genetic risk score (GRS) comprising 97 adult BMI-associated variants among 9,971 women and 6,405 men of European ancestry. Serial measures of BMI were assessed from 18 (women) or 21 (men) years to 85 years of age. We also examined BMI change in early (from 18 or 21 to 45 years of age), middle (from 45 to 65 years of age), and late adulthood (from 65 to 80 years of age). GRS was positively associated with BMI across all ages, with stronger associations in women than in men. The associations increased from early to middle adulthood, peaked at 45 years of age in men and at 60 years of age in women (0.91 and 1.35 kg/m2 per 10-allele increment, respectively) and subsequently declined in late adulthood. For women, each 10-allele increment in the GRS was associated with an average BMI gain of 0.54 kg/m2 in early adulthood, whereas no statistically significant association was found for BMI change in middle or late adulthood or for BMI change in any life period in men. Our findings indicate that genetic predisposition exerts a persistent effect on adiposity throughout adult life and increases early adulthood weight gain in women. [ABSTRACT FROM AUTHOR]

Objective: Glucosamine is a widely used supplement typically taken for osteoarthritis and joint pain. Emerging evidence suggests potential links of glucosamine with glucose metabolism, inflammation, and cardiometabolic risk. We prospectively analyzed the association of habitual glucosamine use with risk of type 2 diabetes (T2D) and assessed whether genetic susceptibility and inflammation status might modify the association.Research Design and Methods: This study analyzed 404,508 participants from the UK Biobank who were free of diabetes, cancer, or cardiovascular disease at baseline and completed the questionnaire on supplement use. Cox proportional hazards models were used to evaluate the association between habitual use of glucosamine and risk of incident T2D.Results: During a median of 8.1 years of follow-up, 7,228 incident cases of T2D were documented. Glucosamine use was associated with a significantly lower risk of T2D (hazard ratio 0.83, 95% CI 0.78-0.89) after adjustment for age, sex, BMI, race, center, Townsend deprivation index, lifestyle factors, history of disease, and other supplement use. This inverse association was more pronounced in participants with a higher blood level of baseline C-reactive protein than in those with a lower level of this inflammation marker (P-interaction = 0.02). A genetic risk score for T2D did not modify this association (P-interaction = 0.99).Conclusions: Our findings indicate that glucosamine use is associated with a lower risk of incident T2D. [ABSTRACT FROM AUTHOR]

Objective: Fibroblast growth factor 21 (FGF21) is involved in the regulation of energy balance and adipose metabolism. Our previous genome-wide association study identified genetic variants in the FGF21 region associated with macronutrient intake preference. We investigated whether the FGF21 genotype modified effects of weight-loss diets varying in macronutrient intake on changes in adiposity in a 2-year randomized diet intervention trial.Research Design and Methods: We genotyped FGF21 rs838147 in 715 overweight or obese individuals who were assigned to one of four diets varying in macronutrient contents. A DEXA scan was performed to evaluate body composition.Results: We observed a significant interaction between the FGF21 genotype and carbohydrate/fat intake on 2-year changes in waist circumference (WC), percentage of total fat mass, and percentage of trunk fat (P = 0.049, P = 0.001, and P = 0.003 for interaction, respectively). In response to the low-carbohydrate/high-fat diet, carrying the carbohydrate intake-decreasing C allele of rs838147 was marginally associated with less reduction in WC (P = 0.08) and significantly associated with less reduction of total fat mass (P = 0.01) and trunk fat (P = 0.02). Opposite genetic associations with these outcomes were observed among the high-carbohydrate/low-fat diet group; carrying the C allele was associated with a greater reduction of WC, total body fat mass, and trunk fat.Conclusions: Our data suggest that FGF21 genotypes may interact with dietary carbohydrate/fat intake on changes in central adiposity and body fat composition. A low-calorie, high-carbohydrate/low-fat diet was beneficial for overweight or obese individuals carrying the carbohydrate intake-decreasing allele of the FGF21 variant to improve body composition and abdominal obesity. [ABSTRACT FROM AUTHOR]

Recent evidence suggests that the fat mass and obesity-associated gene (FTO) genotype may interact with dietary intakes in relation to adiposity. We tested the effect of FTO variant on weight loss in response to 2-year diet interventions. FTO rs1558902 was genotyped in 742 obese adults who were randomly assigned to one of four diets differing in the proportions of fat, protein, and carbohydrate. Body composition and fat distribution were measured by dual-energy x-ray absorptiometry and computed tomography. We found significant modification effects for intervention varying in dietary protein on 2-year changes in fat-free mass, whole body total percentage of fat mass, total adipose tissue mass, visceral adipose tissue mass, and superficial adipose tissue mass (for all interactions, P < 0.05). Carriers of the risk allele had a greater reduction in weight, body composition, and fat distribution in response to a high-protein diet, whereas an opposite genetic effect was observed on changes in fat distribution in response to a low-protein diet. Likewise, significant interaction patterns also were observed at 6 months. Our data suggest that a high-protein diet may be beneficial for weight loss and improvement of body composition and fat distribution in individuals with the risk allele of the FTO variant rs1558902. [ABSTRACT FROM AUTHOR]