Type 2 Diabetes is the commonest form of diabetes and is more likely to develop in people with:
Typically, the diagnosis is made incidentally on routine blood tests, because the hyperglycaemia is gradual and asymptomatic. Prior to the diagnosis, your patient will be hyperinsulinaemic as a response to insulin resistance.
Clues to insulin resistance
The clinical clues to hyperinsulinemia are:
Look for tanned, velvety skin in the axillae, nape of the neck and dorsal aspects of metacarpophalangeal joints and interphalangeal joints.
Given the main trigger for insulin production is consumption of carbohydrate, it makes sense to reduce dietary intake of carbohydrate in favour of low-carbohydrate vegetables, healthy fats and proteins. This will delay the progression to overt type 2 diabetes. See Lifestyle section.
Most of these features improve very quickly by reducing the intake of sugar and carbohydrate generally.
This is seen in people with hyperinsulinemia and dysregulated insulin secretion. It is a feature of pre-diabetes and in the early years of type 2 diabetes. It is an overreaction of insulin secretion in response to eating food that is high in sugar or high glycaemic index carbohydrates.
Symptoms of hypoglycaemia develop 2 – 3 hours after the meal, so they typically occur at morning tea and afternoon tea time, or before the next meal. Typical symptoms of hypoglycemia – sweating, light-headedness, agitation and anxiety, hunger, tremor and palpitations – are relieved by eating or drinking something sweet. Glucose levels can get down to below 3 mmol/L.
Treatment is to avoid high-sugar foods and drinks and changing high-glycaemic index carbohydrate foods to low-GI carbohydrates. Reducing carbohydrate intake overall will improve symptoms and reduce the progression to overt type 2 diabetes.
Diagnosing Type 2 Diabetes
The diagnosis of Type 2 diabetes is made when the HbA1c is above 6.5%. This is a blood test which reflects the blood glucose level for the past 3 months. It is recommended as an annual test to screen for diabetes in people who are at high risk.
At HbA1c values above 6.5%, there is a sharp increase in the risk of blood vessel disease, including heart disease. So, that is why this value is the cut off for diagnosis of diabetes.
In the past, the oral glucose tolerance test was used to diagnose diabetes. It is a cumbersome and time-consuming test, so it was replaced by the single blood test for HbA1c.
Interpreting the oral glucose tolerance test result
The oral glucose tolerance test was the traditional method for diagnosing diabetes, but it has now been replaced by the much easier blood test for HbA1c.
The patient is required to fast, and then drink a 75g load of glucose. Blood tests are collected before the drink, at 1 hour and at 2 hours.
If your patient has had an abnormal result on the oral glucose tolerance test, but the HbA1c is below 6.5%, which one do you believe? The Hba1c is the better test. It predicts the risk for actual disease (diabetes complications) better than the OGTT.
Understanding the progression of Type 2 Diabetes
Type 2 Diabetes is a progressive disease that starts years earlier with insulin resistance. This persists throughout someone’s whole diabetes career and increases with age, weight gain and poor diet. It is when insulin becomes deficient that glucose levels rise. This explains the progressive stages of diabetes – pre-diabetes and overt type 2 diabetes.
Dangers of too much insulin
Hyperinsulinemia is present well before diabetes is diagnosed and explains the typical features of insulin resistance (see Clues to insulin resistance). High levels of circulating insulin – both endogenous and insulin treatment – can have harmful non-glucose effects, including: