Chapter 20: Diabetes mellitus

INTRODUCTION

Diabetes comes from a Greek word meaning ‘to pass or flow through’ (i.e. excessive urination) and mellitus means ‘sweet’. It is a disease caused by a relative or absolute deficiency of insulin.

There are two main types of diabetes (see TABLE 20.1).

• Type 1 is also known as juvenile onset diabetes or insulin dependent diabetes mellitus (IDDM).

• Type 2 is also known as maturity onset diabetes or non-insulin dependent diabetes mellitus (NIDDM).

Type 1 has an autoimmune causation which is also responsible for a late-onset form known as late onset autoimmune diabetes in adults (LADA).

DIABETES: A REAL MASQUERADE

The onset of type 2 diabetes can be subtle and by stealth. Studies have demonstrated that it takes, on average, 7–9 years before a patient is diagnosed.¹ At any one given time almost half of patients with type 2 diabetes are undiagnosed. In 2014–15, around 5% of Australians had diabetes.² A further 16% have impaired fasting glucose or impaired glucose tolerance.³ Very importantly, about 35% of newly diagnosed diabetic patients are already harbouring complications of diabetes.¹ The challenge for GPs is to be on constant lookout for these patients, especially those at risk. Type 2 diabetes is becoming more prevalent in industrial countries—partly due to the ageing population and partly because our lifestyle encourages us to ‘eat more and walk less’.³ Furthermore, 60% of our population are overweight or obese.

Complications occur in type 2 diabetes as well as in type 1.

• Several causes of secondary diabetes are uncommon (pancreatic disease; approx. 2.5%) or very uncommon (see TABLE 20.2).