Diabetes mellitus

Types of DM

DM type 2 is characterised by hyperglycemia and variable degrees of insulin deficiency and resistance. Accounts for 90% of diabetes un adults

DM type 1 is characterised by destruction of the pancreatic beta cells leading to absolute insulin deficienc. Accounts fod 10% of diabetes in adults.
 Testing for islet cell antibodies (ICA) or other islet autoantibodies (antibodies to glutamic acid decarboxylase [GAD] 65, insulin, and to the tyrosine phosphatases, insulinoma-associated protein 2 [IA-2] and IA-2 beta, and zinc transporter ZnT8) in serum may be helpful if establishing the diagnosis is important. 

LADA (Latent autoimmune diabetes in adults) is DM with debut in adult ages that progresses to a insulin dependent phase. These patients may be  ICA or GAD antibodies positive.

Maturity onset diabetes of the young — Maturity onset diabetes of the young (MODY) is a clinically heterogeneous disorder characterized by non-insulin dependent diabetes diagnosed at a young age (<25 years) with autosomal dominant transmission and lack of autoantibodies [1]The diagnosis of MODY is made by performing diagnostic genetic testing by direct sequencing of the gene. It has features of both impaired insulin secretion and insulin resistance. 

Diseases of the exocrine pancreas 
Diseases that damage the pancreas, or removal of pancreatic tissue, can result in diabetes. Ex: pancreatectomy, pancreas cancer, pancreatitis, hemocromatosis. It uw usually insulin requiring but is even more prone to hypoglycemia than DM because glucagon producing cells are also demaged.

DRUG-INDUCED HYPERGLYCEMIA — Drugs can impair glucose tolerance by decreasing insulin secretion, increasing hepatic glucose production, or causing resistance to the action of insulin.
Included in this list are glucocorticoids, oral contraceptives, several classes of antihypertensive drugs such as beta blockers, thiazide diuretics, nicotinic acid, statins, protease inhibitors used for the treatment of human immunodeficiency virus (HIV) infection, gonadotropin-releasing hormone (GnRH) agonists used for the treatment of prostate cancer, tacrolimus

When to look for  antibodies?

We measure autoantibodies when the diagnosis of type 1 or type 2 diabetes is uncertain by clinical presentation:

●In patiens with poor response to initial therapy with sulfonylureas or metformin

●Personal or family history of autoimmune disease

●Overweight or obese children or adolescents presenting with apparent type 2 diabetes, who actually may have an early presentation of type 1 diabetes

References:

1. A difference between the inheritance of classical juvenile-onset and maturity-onset type diabetes of young.people. Tattersall RB, Fajans SS, Diabetes. 1975;24(1):44
2.Drug-induced hyperglycemia Luna B, Feinglos MNJAMA. 2001;286(16):1945.