Latent auto immune diabetes of adulthood (LADA)

LADA has an auto-immune aetiology like T1DM but tends to present later in life than classical T1DM and often runs a more indolent course, with a slow insidious onset. Indeed some authorities only recognise LADA as a variant of T1DM. Historically, also known as 'type one and a half diabetes'.

 Has the patient been drinking more than usual and passing urine more frequently than usual?

Polyuria and polydipsia are the cardinal symptoms of diabetes and occur when the blood glucose level exceeds the renal threshold for glucose excretion - usually approximately 10 mmol/L.

Has the patient noticed a change in eyesight - particularly an inability to focus?

 Difficulty with focusing - that has been present for only a short period and may be fluctuating - is due to osmotically driven swelling of the lens and varies as the degree of hyperglcaemia varies.

Has there been any weight loss?

Weight loss is a cardinal symptom of insulin deficiency and arises due to a combination of lack of anabolic effects of insulin, negative caloric balance due to glycosuria and some contribution from dehydration.

However, the weight loss in LADA is usually less pronounced than in classical T1DM and the whole tempo of the clinical presentation in LADA is slower than in T1DM. Indeed, in a proportion of cases, the patient is overweight at presentation and clinically it can be very difficult to distinguish LADA from T2DM in some cases - the distinction only becoming apparent in hindsight when the patient has rapidly progressed to requiring insulin.

Has there been any pruritus?

Pruritis is a classical symptom of hyperglycaemia although not seen as commonly as the osmotic symptoms.

Is there a family history of diabetes?

LADA is less heritable than T2DM. A family history will also help to detect rare monogenic causes of diabetes such as MODY (maturity onset diabetes of youth), mitochondrial diabetes or APECED (autoimmune polyendocrinopathy, candidiasis and ectodermal dystrophy) that might otherwise be missed.

 Is there a history of other auto-immune diseases?

The coexistence of auto-immune thyroid disease, auto-immune adrenal cortical failure or auto-immune premature ovarian failure suggests the diagnosis of Schmidt’s syndrome and raises the likelihood that the patient may develop further auto-immune conditions. A low threshold should therefore be used for testing for other auto-immune conditions.

The coexistence of diabetes with auto-immune hypoparathyroidism, adrenal cortical failure, recurrent mucocutaenous candidiasis and the presence of ectodermal dystrophic features (e.g. hypoplastic nails, alopecia, lens opacities) means that the very rare APECED (Auto-immune poly-endocrinopathy, candidiasis and ectodermal dystrophy) syndrome is likely to be the diagnosis.

 

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