II Consenso de la Sociedad Chilena de Endocrinología y Diabetes sobre resistencia a la insulina

Insulin resistance is a prevalent condition commonly associated with unhealthy lifestyles. It affects several metabolic pathways, increasing risk of abnormalities at different organ levels. Thus, diverse medical specialties should be involved in its diagnosis and treatment. With the purpose of unifying criteria about this condition, a scientific-based consensus was elaborated. A questionnaire including the most important topics such as cardio-metabolic risk, non-alcoholic fatty liver disease and polycystic ovary syndrome, was designed and sent to national experts. When no agreement among them was achieved, the Delphi methodology was applied. The main conclusions reached are that clinical findings are critical for the diagnosis of insulin resistance, not being necessary blood testing. Acquisition of a healthy lifestyle is the most important therapeutic tool. Insulin-sensitizing drugs should be prescribed to individuals at high risk of disease according to clinically validated outcomes. There are specific recommendations for pregnant women, children, adolescents and older people.

Evaluación de la insulinemia post carga oral de glucosa como método diagnóstico de resistencia a la insulina / Evaluation of serum insulin levels after an oral glucose load for the diagnosis of insulin resistance

Background: In our country, the assessment of insulin resistance (IR) measuring serum insulin levels at 60 and 120 minutes after a 75 g oral glucose tolerance test (OGTT), is usual. However, there is no information about the distribution of serum insulin levels in the Chilean population. Aim: To assess the distribution of serum insulin levels at 60 and 120 minutes during OGTTs and suggest a statistical cut-off point to estimate the degree of IR. Material and Methods: Retrospective analysis of 1815 OGTTs performed in non-diabetic subjects aged between 18 and 75 years, at a university medical center. HOMA-IR (Homeostasis Model Assessment), insulin sensitivity index of Matsuda (ISI-Composite), and their correlation with serum insulin levels at 60 and 120 minutes were calculated. Results: The 75th percentiles for serum insulin levels at 60 and 120 minutes were 127 and 81 µU/mL, respectively. There was a high correlation between HOMA-IR and ISI-Composite (r = -089, p < 0.001). There was a weaker although significant correlation between HOMA-IR and ISI-Composite and insulin levels at 60 (r = 0.56 and -0.79 respectively, p < 0,001) and 120 minutes (r = 0.54 and -0.75 respectively, p < 0,001). Conclusions: We propose 60 and 120 min serum insulin levels of 130 and 80 µU/mL respectively, as cut-off values for normality during OGTT in Chilean normoglycemic individuals.

Evaluación de la ingesta dietética y excreción urinaria de sodio y potasio en adultos / Assessment of dietary intake and urinary excretion of sodium and potassium in adults

Background: Hypertension is associated with elevated sodium and low potassium intakes. The determination of sodium and potassium intake by dietary records is inaccurate, being its measurement from 24-h urine collection the reference method. Aim: To determine urinary sodium and potassium excretion in adults. To compare dietary sodium and potassium intake and their excretion from an isolated urine sample against the reference method. Material and Methods: Seventy healthy adults aged 35 ± 8 years with a body mass index 25 ± 2 kg/m² (36 women) were studied. Urine was collected over 24 h, including an isolated urine sample taken in fasting conditions. Additionally, three 24-h dietary records were performed. Results: Reported sodium and potassium intake was 2,720 ± 567 and 1,068 ± 433 mg/day, respectively. In turn, urinary excretion of sodium and potassium was 4,770 ± 1,532 and 1,852 ± 559 mg/day, respectively. These latter values were significantly higher than those obtained by dietary records. Furthermore, the urinary sodium and potassium excretion estimated from an isolated urine sample was 4,839 ± 1,355 and 1,845 ± 494 mg/day, respectively. These values were similar to those obtained with a 24 h urine collection. Conclusions: Dietary records underestimated electrolyte intake when compared with the reference method. Using an isolated urine sample to estimate electrolyte intake may be a reliable alternative.

Expansibilidad del tejido adiposo en la homeostasis metabólica / Expandability of adipose tissue in metabolic homeostasis

The ability to expand adipose tissue mass may prevent ectopic lipid accumulation and insulin resistance in response to energy oversupply and high-fat diet. Indeed, mice fed with a high-fat diet that overexpresses adiponectin (a lipogenic gene) and are leptin-deficient develop massive obesity; however, have better metabolic profile than leptin-deficient control mice. Furthermore, mice with a deletion of PPARg2 gene (an adipogenic transcription factor) have impaired adipogenic capacity and ability to expand fat mass. These animals in response to a high-fat diet are leaner and present severe insulin resistance. In humans, some of the most striking relevance of adipose tissue for metabolic control came from patients suffering of generalized lipodystrophy. On them, there is an inability to develop subcutaneous adipose tissue, which is accompanied by elevated ectopic lipid accumulation and insulin resistance. Based on this and other evidence, the role of adipose tissue as a buffering lipid tissue controlling whole-body glucose and lipid homeostasis has gained relevance. I hereby further expand on this concept and highlight future research...