Glycemic Index (GI) or Glycemic Load (GL) and Dietary Interventions for Optimizing Postprandial Hyperglycemia in Patients with T2 Diabetes: A Review.

The increasing prevalence of type 2 diabetes (T2D) worldwide calls for effective approaches to its management. Strategies for diabetes have generally focused on optimizing overall glycemic control as assessed by glycated hemoglobin (HbA1c) and fasting plasma glucose (FPG) values. However, since 2001, the American Diabetes Association has established postprandial glucose (PPG) as an independent contributor to both HbA1c and diabetes complications, and increasing evidence suggests that all three glycemic parameters of HbA1c, FPG, and postprandial glucose (PPG) are independently important. OBJECTIVES: The objective of this review was to comprehensively summarize the literature on the effects of nutritional strategies incorporating glycemic index (GI)/glycemic load (GL) on the postprandial hyperglycemia in people with T2D, as well as to provide recommendations for effective dietary strategies addressing both the dietary glycemic index and load in clinical practice. DESIGN: An advanced Pubmed search was conducted. A total of 10 randomized controlled studies met the inclusion criteria. Six studies compared low-GI with higher GI meals, three included studies that compared reduced carbohydrate content with higher carbohydrate content, and one study compared meals of low-GI (with high or low fiber) with meals of higher GI (with high or low fiber). RESULTS: Most of the clinical trials resulted in significant improvement (p < 0.05) of postprandial hyperglycemia. Conclusions: Either reducing the amount of carbohydrate in a meal or increasing consumption of soluble fiber has a favorable effect on postprandial glucose excursions.

Balanced caloric macronutrient composition downregulates immunological gene expression in human blood cells-adipose tissue diverges.

Cardiovascular disease, obesity, and type 2 diabetes are conditions characterized by low-grade systemic inflammation, strongly influenced by lifestyle, but the mechanisms that link these characteristics are poorly understood. Our first objective was to investigate if a normocaloric diet with a calorically balanced macronutrient composition influenced immunological gene expression. Findings regarding the suitability of blood as biological material in nutrigenomics and gene expression profiling have been inconclusive. Our second objective was to compare blood and adipose tissue sample quality in terms of adequacy for DNA-microarray analyses, and to determine tissue-specific gene expression patterns. Blood and adipose tissue samples were collected for gene expression profiling from three obese men before, during, and after a 28-day normocaloric diet intervention where each meal contained an approximately equal caloric load of macronutrients. Time series analyses of blood gene expression revealed a cluster of downregulated genes involved in immunological processes. Blood RNA quality and yield were satisfactory, and DNA-microarray analysis reproducibility was similar in blood and adipose tissue. Gene expression correlation between blood and adipose tissue varied according to gene function, and was especially low for genes involved in immunological and metabolic processes. This suggests that diet composition is of importance in inflammatory processes in blood cells. The findings also suggest that a systems biology approach, in which tissues are studied in parallel, should be employed to fully understand the impact of dietary challenges on the human body.

Vitamin D status in Norwegian children and adolescents with excess body weight.

OBJECTIVES: The prevalence of childhood and adolescent obesity has increased during the past decades. A high body mass index (BMI) is associated with a low vitamin D status. The purpose of this study was to determine the prevalence of vitamin D deficiency and insufficiency in Norwegian children and adolescents with excess body weight. METHODS: Vitamin D status and seasonal variations of 25(OH)D and 1,25(OH)(2)D were analyzed in 102 children and adolescents (70 girls and 32 boys), 8-19 yr of age, with overweight and obesity. RESULTS: Overall, 50% of the children and adolescents included in the study had a low vitamin D status (25(OH)D <75 nmol/L) and 19% had vitamin D deficiency (25(OH)D <50 nmol/L). This was most prevalent in adolescents. Only 42% of teenagers had 25(OH)D levels ≥75 nmol/L vs. 72% of preteens. Both 25(OH)D and 1,25(OH)(2)D showed seasonal variations. A peak in serum 25(OH)D concentrations was observed during the summer while the lowest values were seen during the spring. In contrast, serum 1,25(OH)(2)D had a peak during the spring and the lowest concentrations during the winter. CONCLUSIONS: The prevalence of vitamin D deficiency and insufficiency is higher in obese and overweight adolescents than in overweight children. This might be related to low outdoor activities and low vitamin D intake in teenagers. Seasonal variations of both the vitamin D metabolites were observed.

Serum 25-hydroxyvitamin D is a predictor of serum 1,25-dihydroxyvitamin D in overweight and obese patients.

Recent research suggests that 1,25-dihydroxyvitamin D [1,25(OH)(2)D], a steroid hormone that regulates calcium homeostasis, may also play a role in the development and progression of cancer, multiple sclerosis, cardiovascular, and other diseases. Decreased serum 1,25(OH)(2)D concentrations are often observed in overweight and obese patients. However, little is known about the factors that may influence 1,25(OH)(2)D renal synthesis, because it is generally accepted that serum 1,25(OH)(2)D concentration is strictly regulated by parathyroid hormone and serum concentrations of calcium and phosphorus. In this study, the associations among serum 1,25(OH)(2)D, serum 25-hydroxyvitamin D [25(OH)D], and body composition were analyzed in 1779 patients with excess body weight registered in a Metabolic and Medical Lifestyle Management Clinic in Oslo, Norway. According to our results, serum 25(OH)D, adiposity, age, season of blood sampling, and gender directly influence serum 1,25(OH)(2)D (r = 0.33; P < 0.001), with serum 25(OH)D being the strongest predictor for serum 1,25(OH)(2)D. The 1,25(OH)(2)D concentrations were 25.4 pmol/L (95% Cl: 19.3-31.5; P < 0.001) lower in the lowest 25(OH)D quartile to compared with highest quartile. A seasonal variation was observed for both vitamin D metabolites. Thus, our results suggest that in patients with excess body weight, serum 1,25(OH)(2)D concentrations were associated with 25(OH)D and varied during the year. Therefore, it may also be valuable to measure both serum 25(OH)D and 1,25(OH)(2)D for the evaluation of vitamin D status in overweight and obese persons.

The dependency of vitamin D status on body mass index, gender, age and season.

BACKGROUND: Obesity is a rapidly growing health problem in most developed countries. Excess body weight is a risk factor for many somatic and even psychological disorders, including cardiovascular disease, type 2 diabetes mellitus, osteoarthritis and several cancer types. Recently, overweight and obesity have been shown to be related to low vitamin D status. MATERIALS AND METHODS: The 25(OH)D3 status was analyzed in a population of 2,126 patients registered in a Metabolic and Medical Lifestyle Management Clinic in Oslo, Norway. Seasonal variation and prevalence of vitamin D deficiency were assessed in different body mass index (BMI), sex and age categories. RESULTS: For both sexes and both age groups (<50 years and > or = 50 years) there was a significant decrease of serum 25(OH)D3 levels with increasing BMI. Surprisingly, not only were the 25(OH)D3 levels negatively correlated with BMI, but the serum 1,25(OH)2D3 levels were also. The seasonal variation of serum 25(OH)D3 was highest in young (<50 years) non-obese men. The prevalence of vitamin D deficiency was highest in individuals with BMI > or = 40, being as high as 32% among women and 46% among men. CONCLUSION: The 25(OH)D3 level, as well as its seasonal variation and the prevalence of vitamin D deficiency, are all dependent on BMI, and age separately. The results of the study suggest that 1 in 3 women and 1 in 2 men with BMI > or = 40 are vitamin D deficient.

Seasonal variation of 1,25-dihydroxyvitamin D and its association with body mass index and age.

Under most normal conditions the serum level of 1,25-dihydroxyvitamin D is constant throughout the year, due to tight biochemical regulation. In contrast to this, the level of 25-hydroxyvitamin D is variable through the year, being largest in late summer, due to photosynthesis in the skin. The vitamin D status is usually assessed by measuring the level of the latter vitamin D derivative, rather than that of the presumably most active derivative 1,25(OH)2 vitamin D.We here show that for persons with a high body mass index (BMI) there is a significant seasonal variation, not only of 25(OH) vitamin D, but also of 1,25(OH)2 vitamin D. The variation seems to be largest for those with the poorest vitamin D status. Furthermore, there seems to be a correlation between the levels of the two vitamin D metabolites, indicating that the regulation of 1,25(OH)2 vitamin D is not always tight, notably in persons with high BMI.

Serum 1,25-dihydroxy vitamin D is inversely associated with body mass index.

BACKGROUND: Based on in vitro studies, it has been hypothesized that 1,25-dihydroxy vitamin D (1,25-vit D) may promote weight gain in humans, but previous studies have demonstrated conflicting results regarding the association between serum 1,25-vit D and body mass index (BMI). AIM OF THE STUDY: To evaluate the relation between serum 1,25-vit D and BMI. METHODS: Two thousand one hundred and eighty-seven subjects, recruited from a metabolic and medical lifestyle management clinic, were included in a cross-sectional study. BMI, 25-hydroxy vitamin D (25-OH-vit D) and 1,25-vit D were measured. The cohort was divided according to BMI in five groups (<25, 25-29.9, 30-34.9, 35-39.9 and >39.9 kg/m(2)). Statistical analyses were performed with multiple linear regression models. Age and gender were used as explanatory covariates. RESULTS: With increasing BMI group, there was a significant decrease in both serum 25-OH-vit D and 1,25-vit D (P<0.001). Those with BMI >39.9 kg/m(2) had 24% lower serum 25-OH-vit D levels and 18% lower 1,25-vit D levels than those with BMI <25 kg/m(2). CONCLUSIONS: There is an inverse association between BMI and the serum levels of 25-OH-vit D and 1,25-vit D. This makes it highly unlikely that high levels of circulating 1,25-vit D contribute to the development of obesity.

[Insulin-using woman with type 2 diabetes and weight problems]. / Kvinnelig insulinbruker med diabetes type 2 og vektproblemer.

A 61-year-old overweight woman had been diagnosed with diabetes mellitus, hypertension and hypothyreosis. Treatment with antidiabetic and antihypertensive medication and thyroxine had been started. Blood sugar had been increasing despite medication and she had started using insulin. In 2003 she used 150 IE insulin per day. She tried hard to adhere to a recommended diet, but gradually became fatter, maximum weight was 120 kg. She started on a low carbohydrate diet on her own and lost 14 kg during 5 months. She had some hypoglycemic episodes and sought advice at Dr. Fedon Lindberg's Clinic. Her low carbohydrate diet was continued, endurance exercise was included, medication with metformin was started and during 8 months she was off insulin and showed much lower blood sugar values than before. She lost 14 kg during this period. She was motivated for loosing more weight and starter on a VLCD (very low caloric diet). She lost another 9 kg on this diet. She than started regular resistance training and her weight stabilized on 80 kg. Her HbA1c value has been reduced from 8.9 to 5.4% and her total/HDL cholesterol ratio has been reduced from 5.4 to 1.7. Her C-peptide value increased in the period when insulin was reduced, but is now reduced to 700 pmol/L. Micro-CRP has been reduced from 9.0 mg/L to 0.4 mg/L. With a low carbohydrate diet and exercise this woman no longer has diabetes or severe overweight. It is our opinion that many patients with type 2 diabetes can manage without medication (especially insulin) by reducing the intake of carbohydrates considerably.