Diabetes: pitfalls in diagnosis and early management

Dr Bobby Huda, consultant in diabetes and metabolism at St Bartholomew’s and Royal London Hospitals, describes the different types of diabetes and how they are diagnosed.

[DIABETES IS A LIFE-LONG CONDITION wherein the blood glucose levels are higher than normal. The vast majority (90%) of cases are type 2 diabetes, with around 10% type 1 diabetes or atypical cases.

Type 1 diabetes

People with type 1 diabetes are usually diagnosed in childhood or as a young adult. It often presents as a diabetes emergency with high blood glucose and ketones in the blood from lack of insulin. They will usually need to be admitted to hospital. They will need to take lifelong insulin, as in most cases their pancreas will eventually stop making any insulin altogether.

Management can be difficult as it is difficult to match insulin to food and exercise. Some people with type 1 diabetes use an insulin pump, for greater precision with their doses, and a glucose sensor to monitor glucose regularly.

Type 2 diabetes

With type 2 diabetes, people are usually diagnosed at a later age – 50s and onwards – and the prevalence increases with age. People of ethnic minority origin have a higher prevalence of type 2 diabetes and may be diagnosed at a younger age.

Many people with type 2 diabetes have a ‘pre-diabetes’ phase which can last for several years. There is a strong genetic component with type 2 diabetes.

People with type 2 diabetes still produce their own insulin, but are ‘insulin resistant’– usually down to being overweight. They may control their blood glucose with lifestyle measures only at first – diet and exercise – but then often need oral medications and sometimes insulin: currently about 17% of people with type 2 diabetes are taking insulin.

Diagnosis

People with diabetes usually present with the classic symptoms of increased thirst, increased urine frequency and weight loss. Other symptoms include fatigue and blurred vision. The formal diagnosis is made by fasting glucose, glycated haemoglobin (HbA1c) or an oral glucose tolerance test (OGTT); with fasting glucose or HbA1c the test should be repeated on a different day. However, if people are symptomatic and have a raised random glucose, it is adequate for diagnosis.

Occasionally, diabetes can present as an emergency (diabetic ketoacidosis) and it is almost always in cases of type 1 diabetes. People with type 1 diabetes tend to be young and otherwise healthy; therefore type 1 diabetes can sometimes be misdiagnosed as other conditions – for example, urine tract infection – and the delay in diagnosis can be dangerous and occasionally life threatening. That would usually occur in primary care, but could also happen in a busy A&E department with junior medical staff.

The onset of type 2 diabetes is more gradual, so it would be rare to have an emergency presentation. As described above, there is likely to be a condition where an individual has ‘pre-diabetes’– where they are borderline for diabetes. This could lead to a delay in diagnosis.

People with ‘pre-diabetes’ are often followed annually for many years with a blood test before developing type 2 diabetes. Appointments can be missed, communication can break down and occasionally a diagnosis could be delayed by some years. This could lead to complications.

Gestational Diabetes Mellitus (GDM)

That is impaired glucose tolerance that develops during pregnancy. Screening for GDM in the UK is guided by NICE Diabetes in Pregnancy guidelines and is triggered by risk factors such as a BMI of greater than 30 kg/m2, ethnic origin, family history, previous GDM or previous large baby.

Gestational diabetes is diagnosed by an OGTT at 24-28 weeks gestation in most cases. Missing GDM can be serious with a baby being large for gestational age, potentially leading to obstetric complications such as difficult labour, shoulder dystocia, unstable lie and increased chances of caesarean section. There are also associations with maternal health, including gestational hypertension and pre-eclampsia. Rarely, missed GDM can be associated with stillbirth or diabetic fetopathy.

Early management

The management regime for type 1 diabetes is to start insulin immediately. Type 2 diabetes is usually treated with lifestyle measures initially, and then followed by oral medications. GDM is managed by diet and then metformin or insulin. A delay or misdiagnosis of the type of diabetes can mean a delay in starting insulin – when it is misdiagnosed as type 2 diabetes – or inappropriate insulin – when it is misdiagnosed as type 1 diabetes – and lead to side effects of weight gain or hypoglycaemia (low blood glucose).

Usually the diagnosis of diabetes is straightforward and takes place in primary care. However, with increasing numbers of people with diabetes being diagnosed, systems are often under strain and cases can be missed or mis-diagnosed. q • To contact Dr Huda call 020 3594 6058 / 07919 924925, email bobby.huda1@nhs.net alternatively visit londondiabetes.com or clevelandcliniclondon.uk