Atypical presentation of diabetes: case study

Dr Pipin Singh describes the case of a 45-year-old man with apparent type 2 diabetes who was unintentionally losing weight.

Mr B, a 45 year old man, presented with a six-month history of fatigue and anxiety-type symptoms. He reported no other specific physical symptoms. His blood pressure was normal and urinalysis was negative for glucose and ketones. His BMI was 32kg/m2 and he reported a family history of type 2 diabetes on his maternal side. Routine blood tests revealed an HbA1c of 72mmol/mol, but were otherwise unremarkable.

I diagnosed him with type 2 diabetes, based on his BMI and family history.  I started him on metformin and referred him to the dietitian. His metformin was uptitrated over three weeks and he reported no adverse effects to the medication.

One month later, he attended for follow up and reported polyuria and some weight loss.  He had become increasingly stressed because of his life circumstances and put some weight loss down to this. I checked his weight and noted that he had lost 5kg since his initial appointment four weeks earlier. Urinalysis remained negative.

Based on his symptomatology, I started him on gliclazide and gave him a meter, strips and lancets. He was given appropriate counselling about blood sugar monitoring, DVLA rules and hypoglycaemia. The dose of gliclazide was escalated over six weeks to maximum dose.

At his review appointment he reported that he had been concordant with the medication, but his blood sugars were between 15 and 20mmol/L, he was continuing to lose weight and his HbA1c had risen to 84mmol/mol. He reported feeling more tired and on direct questioning reported increasing thirst. Urinanalysis at this time revealed glucose and ketones.

I discussed this case with the diabetologist on call and my patient was assessed that day. He subsequently started humulin M3 twice daily. His blood sugars stabilised and he felt better within two weeks of initiation of the insulin. A diagnosis of late-onset type 1 diabetes was made.

Late-onset type 1 diabetes

Late-onset type 1 diabetes  (latent autoimmune diabetes in adults or LADA)  presents in adulthood. It is an absolute loss of insulin and is thought to be autoimmune in origin. Patients will require insulin to prevent diabetic ketoacidosis.

In patients aged 30-50 years, type 1 diabetes accounts for 13% of all new cases of diabetes and the annual incidence is around 7/100,000 in this age group.1

Challenges in primary care

Late-onset type 1 diabetes can resemble type 2 diabetes in a number of ways. In both conditions, patients may have symptoms suggestive of hyperglycaemia and metabolic syndrome.

Initial assessment should be guided by the patient’s weight, family history, and symptoms such as weight loss. Patients with late-onset type 1 diabetes may be overweight, but could be losing significant amounts of weight unintentionally. This weight loss may represent ketogenesis. The presence of ketones on urinalysis could indicate beta-cell failure in the pancreas and the requirement for insulin replacement.

NICE previously suggested using ketonuria as a marker for the need for insulin.2 However, it has been suggested that 20% of patients with late-onset type 1 diabetes do not have ketonuria.3

Other investigations occasionally performed in a hospital setting aim to look at how much insulin is being produced by the pancreas, including C-peptide levels and glutamic acid decarboxylase (GAD) antibodies. These investigations are not routinely used in primary care and need to be interpreted with caution.

This case study highlights the importance of ensuring that patients are reviewed regularly following a diagnosis of diabetes where you suspect the patient may not typically be a type 2 diabetic. Do not be afraid to question the diagnosis at any point.

Practical tips

If your patient has been newly diagnosed with diabetes, is not unwell but does not fit the typical criteria for type 2, then it is entirely reasonable to try a course of metformin with regular assessment of symptoms, weight and urine testing for glucose and ketones.  

If the patient has osmotic symptoms you may consider gliclazide and titrate this to maximum dose over a period of a few weeks, assessing response. Review the patient every two weeks and have a low threshold for referring to your diabetes service if their condition does not behave as typical type 2 diabetes, despite good concordance with medication.

If you are unsure what type of diabetes the patient has, let them know what symptoms may suggest diabetic ketoacidosis so that they can look out for these and are empowered to manage any complications. Explain that you are not sure what type of diabetes they have and that there may be a need for insulin in the future.

Key learning points
  • Consider ketonuria and unintentional weight loss a red flag - these patients are likely to require insulin.
  • Test ketones at initial diagnosis for all patients with diabetes.
  • Do not routinely perform autoantibody testing to differentiate between the types of diabetes.
  • Do not use HbA1c to diagnose type 1 diabetes.
  • If the patient has been diagnosed with type 2 diabetes but the condition is behaving atypically,  reconsider your diagnosis.
  • If you are unsure of the type of diabetes that your patient has, please ensure they have a supply of ketone testing sticks at home until you are happy with the diagnosis and can review this accordingly.

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This is an updated version of an article that was first published in July 2016.


  1. Bruno G, Runzo C, Cavallo-Perin P et al. Incidence of type 1 and type 2 diabetes in adults aged 30-49 years: the population-based registry in the province of Turin, Italy. Diabetes Care 2005;28:2613-9
  2. NICE. Type 1 diabetes: diagnosis and management of type 1 diabetes in children, young people and adults. CG15. London, NICE, 2004. Available from:
  3. Sabbah E, Savola K, Ebeling T et al. Genetic, autoimmune, and clinical characteristics of childhood- and adult-onset type 1 diabetes. Diabetes Care 2000;23:1326-32

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