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Understanding Diabetes

Diabetes has reached epidemic proportions in the developed world, typically in response to our 'self abusive lifestyles'. Understand the disease and its implications for exercise by reading this page.

The physiological cause of diabetes is a poor control of the bodies’ blood sugar levels due to insulin insensitivity or poor insulin production (which we will explain).  The typical symptoms of diabetes include; tiredness, constantly feeling thirsty, and needing to pass urine lots.

The human body has developed a complex system for feeding itself.  Part of this system is designed to break down the starches and sugars which are within the foods we ingest, converting them into our body's ‘basic food source’, glucose, which fuels the majority of activities within the body.

What is normal glucose metabolism?

personal training pancreas diagram

In normal metabolism, the sugars and starches within the foods we eat are broken down into glucose, and are absorbed into the blood stream. This absorption causes a rise in the blood glucose level.

As the blood containing elevated glucose levels circulates, it comes into contact with the pancreas, and certain specific parts of the pancreas, which are contained in a sub structure called the islets of Langerhans.

These specialized parts are the alpha, beta, and delta cells, which produce particular hormones, which drastically affect blood sugar levels.


personal training glucose flow chartWhen an increased blood sugar level is sensed by the beta cells, they secrete insulin directly into the bloodstream.  Insulin is a powerful hormone which allows cell membranes to change, (they become more permeable to glucose), so that they allow the glucose molecule to be pulled into the cell interior, where it can be broken down into energy for immediate use in muscle cells or stored in fat cells for use later.

In another example, when you've just completed some physical work, and your blood sugar level begins to fall, the other type of cell, the alpha cell, senses a low blood sugar condition, and it releases another hormone, called glucagon. Glucagon goes out into the blood stream in the same fashion as the insulin did, however, the glucagon tells the liver cells to release some of their stored sugars back into the blood stream, thus raising the blood sugar levels back into an operating range.

Abnormal glucose metabolism


Many things can happen to unbalance or destroy this human system of absorption and utilization of glucose.  The destruction of beta cells by a virus, or an auto-immune response from our own bodies, are two reasons which have so far been found for beta cell destruction in clinical studies.

When this sort of destruction occurs, it impairs the body's ability to manufacture insulin.  In the case of someone with type 1, insulin-dependent diabetes, the beta cell destruction may be complete and may never be repaired by the body.  In the case of type 2 diabetes, some beta cells remain, however they may not be able to keep up with the body's demand for insulin.

Types of diabetes


There are two main types of diabetes, these are:

1.      Type 1 diabetes: Also known as insulin dependant diabetes mellitus (IDDM), or juvenile diabetes.  Type 1 diabetes is characterised by the loss of the insulin producing beta cells.  As a person with type 1 diabetes doesn’t have these special cells they are required to inject insulin into their body and set times during the day.  Type 1 diabetes accounts for approximately 10% of all diabetes and typically presents early in life in children (or sometimes adults) with healthy body weight.

2.      Type 2 diabetes: Also known as non-insulin dependant diabetes mellitus (NIDDM) or adult onset diabetes.  Type two diabetes accounts for approximately 90% of all diabetes and this is increasing.  Type 2 diabetes is also known as lifestyle diabetes and typically effects overweight and obese adults (and increasingly overweight and obese children) who develop a resistance to insulin and secrete progressively less insulin and hence struggle to control their blood sugar levels.

Hypoglycemia (low blood sugar)


Very low blood sugar levels are the more commonly encountered diabetic incident. Hypoglycaemia can result from missing a meal, too much exercise, injecting too much insulin or injecting it at the wrong time (for example too close to exercise).  The symptoms of hypoglycaemia include: personal training low blood sugars     

  • Shakiness
  • Dizziness
  • Sweating
  • Hunger
  • Headache
  • Clumsiness
  • Difficulty paying attention


When training a client with diabetes (or showing the signs and symptoms of diabetes) you must take special care to gradually build the volume of exercise they take part in so they don’t overdo it initially and become hypoglycaemic.  If you notice any of the tell tale signs of hypoglycaemia then stop the exercise and allow your client to rehydrate and build their blood sugar levels back up with a sugary snack – a sweet, some fruit juice or a piece of fruit.

Hyperglycaemia (high blood sugar)


Elevated blood glucose levels will occur with every diabetic at some point, but continued elevation can be a result of poor blood sugar management.  One of the main conditions to develop as a result of this is ketoacidosis, where excessive levels of ketones build up in the blood.  

When the glucose stays in the blood, and fails to get to the cells of the body, the cells must rely solely on fat for energy.  The by products of breaking down fat, in the absence of carbohydrates are ketone bodies.  The body excretes these ketones in the urine, but when produced in excess they can accumulate in the bloodstream. This causes the pH of the blood to fall (ketoacidosis) and this can be fatal if not treated.  Initial symptoms include:

  • Thirst or a very dry mouth
  • Frequent urination
  • Hyperglycaemia
  • Ketonuria (ketone bodies present in urine)


Other symptoms may then appear including:

  • Shortness of breath
  • A ‘fruity’ smelling breath
  • Nausea
  • Feeling tired constantly
  • Dry skin
  • Confusion


And if ft unchecked these symptoms can lead to:

  • Coronary heart disease
  • Nerve damage – numbness, tingling and pain in feet, skin damage due to altered sensation
  • Kidney damage and failure
  • Eye Damage – impaired vision and eventual blindness
  • Foot complications – development of foot ulcers and sometimes amputations

Treatment of diabetes


For the majority of people with diabetes (type 2) a significant change in lifestyle is required to manage the disease.  This involves altering the diet to include more low fat, low sugar, high fibre foods and less high fat, high sugar fast foods.  It also involves the establishment of regular exercise habits. 

As these lifestyle changes are often significant a personal trainer is (or at least should be) a perfect person to help guide and support these changes.  As most people with diabetes will be taking medication (often for the foreseeable future) then working with their doctor to understand these medications and their effects will also be vital.

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