Low-Glycemic Load Diets and Thyroid Function: A Narrative Review and Future Perspectives.

Nutrition and calorie intake are associated with subtle changes of thyroid function tests in subjects with an intact Hypothalamic-Pituitary-Thyroid axis. Iodine deficiency and extreme fluctuations in calorie intake, such as those that occur during periods of starvation or overfeeding could lead to alterations in thyroid hormones. The dietary macronutrient and micronutrient composition could also influence the thyroid function. Recently, Low-Glycemic Load (LGL) diets have become very popular and are effective in the treatment and/or prevention of several medical conditions, including diabetes, obesity, cardiovascular disease, and epilepsy. In this review, we report on the available data from the literature regarding the association between LGL diets and thyroid function or dysfunction. Several studies conducted in this field to date have yielded inconsistent results.

Repetitiveness of the oral glucose tolerance test in children and adolescents.

BACKGROUND: Data regarding the most suitable diagnostic method for the diagnosis of glucose impairment in asymptomatic children and adolescents are inconclusive. Furthermore, limited data are available on the reproducibility of the oral glucose tolerance test (OGTT) in children and adolescents who are obese (OB). AIM: To investigate the usefulness of the OGTT as a screening method for glucose dysregulation in children and adolescents. METHODS: Eighty-one children and adolescents, 41 females, either overweight (OW), OB or normal weight (NW) but with a strong positive family history of type 2 diabetes mellitus (T2DM), were enrolled in the present observational study from the Outpatient Clinic of Paediatric Endocrinology of the University Hospital of Patras in Greece. One or two 3-h OGTTs were performed and glucose, insulin and C-peptide concentrations were measured at several time points (t = 0 min, t = 15 min, t = 30 min, t = 60 min, t = 90 min, t = 120 min, t = 180 min). RESULTS: Good repetitiveness was observed in the OGTT response with regard to T2DM, while low repetitiveness was noted in the OGTT response with regard to impaired glucose tolerance (IGT) and no repetitiveness with regard to impaired fasting glucose (IFG). In addition, no concordance was observed between IFG and IGT. During the 1st and 2nd OGTTs, no significant difference was found in the glucose concentrations between NW, OW and OB patients, whereas insulin and C-peptide concentrations were higher in OW and OB compared to NW patients at several time points during the OGTTs. Also, OW and OB patients showed a worsening insulin and C-peptide response during the 2nd OGTT as compared to the 1st OGTT. CONCLUSION: In mild or moderate disorders of glucose metabolism, such as IFG and IGT, a diagnosis may not be reached using only one OGTT, and a second test or additional investigations may be needed. When glucose metabolism is profoundly impaired, as in T2DM, one OGTT is probably more reliable and adequate for establishing the diagnosis. Excessive weight and/or a positive family history of T2DM possibly affect the insulin and C-peptide response in the OGTT from a young age.

The role of carbohydrate counting in glycemic control and oxidative stress in patients with type 1 diabetes mellitus (T1DM).

PURPOSE: Oxidative stress is closely related to type 1 diabetes mellitus (T1DM), playing a key role in the pathogenesis of the disease and progression of complications. It is characterized by loss of equilibrium between oxidative factors and antioxidant protective mechanisms. Several markers have been used to assess both components of oxidative status; two of which are malondialdehyde (MDA) and ferric reducing antioxidant power (FRAP). METHODS: We investigated glycated hemoglobin (HbA1c), lipid profile, MDA, and FRAP in 35 patients with T1DM, aged 2-23 years, at the end of two 4-month observational periods: period A: standard insulin dosing per meal, and period B: proper prandial insulin dosing based on the amount of carbohydrates contained in each meal. RESULTS: At the end of period B, (i) glucose control (HbA1c) was improved; (ii) oxidative stress, estimated by MDA, showed a tendency to decrease; and (iii) antioxidant capacity, estimated by FRAP, was significantly increased compared with that of period A. No significant differences were observed in the lipid profile of the patients between the two periods. CONCLUSION: Proper insulin dosing based on carbohydrate counting (CC) may have an impact on the antioxidant defensive mechanisms of patients with T1DM through the attainment of a better glycemic profile. There are also indications that it may reduce MDA, an important biomarker of oxidative stress and a significant mediator of complications in T1DM. Therefore, prompt dietetic intervention using CC as early as possible after the diagnosis of T1DM is important for achieving optimal glycemic control and improved oxidative status.

Protective mechanisms against oxidative stress and angiopathy in young patients with diabetes type 1 (DM1).

OBJECTIVE: Advanced glycation end-products (AGEs) via their receptor, RAGE, are involved in diabetic angiopathy. Soluble RAGE, an inhibitor of this axis, is formed by enzymatic catalysis (sRAGE) or alternative splicing (esRAGE). Malondialdehyde (MDA) is an oxidative stress marker, and ferric reducing ability of plasma (FRAP) is an anti-oxidant capacity marker. METHODS: In isolated mononuclear blood cells from 110 DM1-patients (P) and 124 controls (C) (4-29 years) RAGE mRNA (g) and protein expression (pe) were measured by RT-PCR and Western immunoblotting, respectively. Plasma levels of CML (AGEs) and sRAGE were measured by ELISA, MDA by flurometry and FRAP according to 'Benzie and Strain'. RESULTS: P showed: (i) higher g of RAGE, especially in p>13 years of age and >5 years DM1, (ii) increased pe of esRAGE in DM1>5 years and (iii) increased FRAP and MDA. CONCLUSIONS: The increased esRAGE and FRAP with increased levels of CML and MDA possibly reflects a protective response against the formation of diabetic complications in these young diabetic patients.

Metabolic impact of a ketogenic diet compared to a hypocaloric diet in obese children and adolescents.

BACKGROUND: The effects of carbohydrate-restricted (ketogenic) diets on metabolic parameters in children have been incompletely assessed. OBJECTIVE: To compare the efficacy and metabolic impact of ketogenic and hypocaloric diets in obese children and adolescents. SUBJECTS: Fifty-eight obese subjects were placed on one of the two diets for 6 months. METHODS: Anthropometric measurements, body composition, oral glucose/insulin tolerance test, lipidemic profile, high molecular weight (HMW) adiponectin, whole-body insulin sensitivity index (WBISI), and homeostatic model assessment-insulin resistance (HOMA-IR) were determined before and after each diet. RESULTS: Both groups significantly reduced their weight, fat mass, waist circumference, fasting insulin, and HOMA-IR (p = 0.009 for ketogenic and p = 0.014 for hypocaloric), but the differences were greater in the ketogenic group. Both groups increased WBISI significantly, but only the ketogenic group increased HMW adiponectin significantly (p = 0.025). CONCLUSIONS: The ketogenic diet revealed more pronounced improvements in weight loss and metabolic parameters than the hypocaloric diet and may be a feasible and safe alternative for children's weight loss.