Chapter 11: 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 11.1).

• 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. In 2014–15, around 1.2 million (5%) Australians had diagnosed type 2 diabetes¹ and another 500 000 (2.1%) were estimated to have type 2 diabetes but were not yet diagnosed.² A further 2 million (8.4%) had impaired fasting glucose or impaired glucose tolerance. Around half of those with type 2 diabetes have complications (when microalbuminuria is included), many of whom already have a complication at the time of diagnosis. The challenge for GPs is to be on constant lookout for these individuals, especially those at risk. Type 2 diabetes is becoming more prevalent in industrial countries—due to the ageing population, broadened diagnostic definitions and because our lifestyle encourages us to ‘eat more and walk less’.³ Furthermore, roughly 60% of our population are overweight or obese.

Complications occur in both type 1 and type 2 diabetes.

• Several causes of secondary diabetes are uncommon (pancreatic disease; approx. 2.5%) or very uncommon (see TABLE 11.2).

• Asymptomatic people at high risk of undiagnosed diabetes should be screened ...