impaired glucose tolerance and metabolic syndrome

Impaired Glucose Tolerance (IGT) is most commonly associated with Reactive Hypoglycaemia (RH) and is a leading factor, combined with abdominal fat accumulation, that leads to Metabolic Syndrome (MetS). MetS affects about 47 million (or 24%) of people in the USA, many of whom students who gained the 15 extra pounds dubbed “Freshman 15”. Insulin Resistance plays a key role in the development of this Syndrome as well as IGT and RH. Essentially, however, the same underlying dietary and lifestyle factors cause these problems. And modifying both diet and lifestyle provide both solutions and preventative measures.

Impaired Glucose Tolerance (IGT) and Reactive Hypoglycaemia (RH)

RH where the body releases excessive amounts of insulin in response to raised blood sugar. The result is that excess glucose is removed from the blood causing discomfort chiefly due to stress hormone released to raise blood sugar levels back to normal levels. These adrenaline-related reactions include irritability, anxiety and nerve problems, such as shakiness.

Insulin Resistance (IR) is a leading cause of RH as well as contributor to its onset. Whilst IR may be caused and promoted by excess fat tissue and inflammation, IR programs the body to release excessive amounts of insulin to manage blood glucose levels. This is due to the fact that cells are less sensitive to insulin, thus more insulin is produced (due to blood glucose levels remaining high for a long period of time).

Insulin Resistance (IR) and Metabolic Syndrome (MetS)

IR causes Diabetes, Heart Disease, High Blood pressure, Fatty Liver Disease, Sleep Apnea, Sexual Dysfunction, Impotence and Cancer. IR also causes MetS which itself is a precursor to the onset of many of these diseases and health disorders. MetS is characterised by IGT, high blood cholesterol and triglyceride levels, and upper (abdominal) weight gain. The major contributory factors to MetS are a sedentary lifestyle combined with a diet high in refined carbohydrates – the same factors that cause IR.

To prevent the onset of the above disorders, we need to manage our Insulin levels and ensure our cells are sensitive to Insulin. Key to this is avoiding diets that count calories alone and aim to restrict calorie intake. More important is that the effect of foods on blood sugar be managed – in other words, low Glycemic Index and low Glycemic Load. Meanwhile, exercise is of key importance.

Key term:

Metabolic syndrome is a combination of medical disorders that, when occurring together, increase the risk of developing cardiovascular disease and diabetes

Definitions and diagnosis – different world health organizations have differing specific criteria, but criteria include

  • Raised triglycerides: > 150 mg/dL (1.7 mmol/L), or specific treatment for this lipid abnormality
  • Reduced HDL cholesterol: < 40 mg/dL (1.03 mmol/L) in males, < 50 mg/dL (1.29 mmol/L) in females, or specific treatment for this lipid abnormality
  • Raised blood pressure (BP): systolic BP > 130 or diastolic BP >85 mm Hg, or treatment of previously diagnosed hypertension
  • Raised fasting plasma glucose (FPG): >100 mg/dL (5.6 mmol/L), or previously diagnosed type 2 diabetes
  • Central obesity: waist:hip ratio > 0.90 (male); > 0.80 (female), or body mass index > 30 kg/m2
  • Microalbuminuria: urinary albumin excretion ratio ≥ 20 µg/min or albumin:creatinine ratio ≥ 30 mg/g
  • Other: High-sensitivity C-reactive protein has been developed and used as a marker to predict coronary vascular diseases in metabolic syndrome, and it was recently used as a predictor for nonalcoholic fatty liver disease in correlation with serum markers that indicated lipid and glucose metabolism.

Pathophysiology

Development of visceral fat, after which the adipocytes (fat cells) of the visceral fat increase plasma levels of TNFα and alter levels of a number of other substances (e.g., adiponectin, resistin, and PAI-1)

  • TNFα has been shown not only to cause the production of inflammatory cytokines, but also possibly to trigger cell signaling by interaction with a TNFα receptor that may lead to insulin resistance
  • The increase in adipose tissue also increases the number of immune cells present which play a role in inflammation
  • Chronic inflammation contributes to an increased risk of hypertension, artherosclerosis and diabetes

Risk factors: Stress, Overweight and obesity, Sedentary lifestyle

Stress: prolonged stress can be an underlying cause of metabolic syndrome by upsetting the hormonal balance of the hypothalamic-pituitary-adrenal axis (HPA-axis)

  • Dysfunctional HPA-axis causes high cortisol levels to circulate, which results in raising glucose and insulin levels
  • This in turn causes insulin-mediated effects on adipose tissue, ultimately promoting visceral adiposity, insulin resistance, dyslipidemia and hypertension, with direct effects on the bone, causing “low turnover” osteoporosis
  • HPA-axis dysfunction may explain the reported risk indication of abdominal obesity to cardiovascular disease, type 2 diabetes and stroke

Adapted from:

Murray, M. (2003). How to Prevent and Treat Diabetes. New York, Riverhead Books.

Schwarzbein, D.(2002). The Schwarzbein Principle II: The Transition. Deerfield Beach, Florida, Health Communications, Inc.

Rakel, D. (2007). Integrative Medicine. Philadelphia, PA: Saunders

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