Secondary diabetes mellitus

Secondary diabetes mellitus

Definition

Chronic hyperglycaemia and other metabolic abnormal-ities seen in diabetes mellitus due to another identifiable cause.

Pancreatic disease: At least two thirds of the pancreas must be lost to cause a type 1 diabetes like syndrome. Causes include chronic pancreatitis, post-pancreatectomy, pancreatic cancer, cystic fibrosis or haemochromatosis.

Insulin counter-regulatory hormones inhibit insulin

secretion or cause insulin resistance. This includes drugs and results in a type 2 diabetes like syndrome.

·        Growth hormone (acromegaly)

·        Glucocorticoids (Cushing’s syndrome or disease, iatrogenic)

·        Glucagon (glucagonoma)

·        Catecholamines (phaeochromocytoma)

·        Somatostatin (pancreatic somatostatinoma)

·        Oral contraceptives and pregnancy probably due to the oestrogens (and also increased cortisol seen in pregnancy).

Drugs may inhibit insulin secretion or cause damage to the pancreatic islets.

·        Thiazides and phenytoin inhibit insulin secretion.

·        Pentamidine damages the Î²-cells.

Insulin receptor defects. These are rare disorders and include:

·        DIDMOAD (diabetes insipidus, diabetes mellitus, optic atrophy and deafness)

·        Insulin-resistant diabetes with acanthosis nigricans

1.     Young women who have polycystic ovaries and reduced numbers of insulin receptors due to mutations in the allele for the receptor gene.

2.     Older patients with antibodies to insulin receptors reducing their affinity for insulin.