Mitochondrial diabetes

Mitochondrial diabetes is a group of rare forms of diabetes caused by mutations of the mitochondrial genome. The commonest form of this diagnosis is due to a mutation in the mitochondrial leucine-transfer RNA gene. They are clinically characterised by maternal transmission, and prevalence is between 0.5% and 2% of all diabetes.

Diet

Standard dietary advice is to aim for a negative caloric balance if the BMI is greater than 25 kg/m2. This includes avoiding refined sugars and foods high in saturated animal fats.

However, dietary management alone is rarely, if ever, adequate treatment for mitochondrial diabetes.

Oral hypoglycaemics

Oral hypoglycaemics have a limited role in mitochondrial diabetes and insulin therapy is the mainstay of treatment.

Metformin is contra-indicated because of the risk of lactic acidosis; thiazoledinediones have no role because the defect is not one of insulin sensitivity but of insulin secretion.

Sulphonylureas can sometimes be used in individuals with relatively mild insulin deficiency.

Insulin therapy

Insulin therapy is the mainstay of treatment of mitochondrial diabetes.

Ideally a basal bolus regimen consisting of a once daily long acting insulin and three prandial injections of rapid acting insulin should be used. Alternatively, a twice daily biphasic insulin regimen may be employed but is generally less preferable.

Follow up

Routine annual life-long follow up should be offered. This should include, as a minimum, assessment of HbA1c, renal function and urinary albumin excretion; fasting lipids should also be performed as well as annual examination for retinopathy, neuropathy and BP.

Diabetesbible is for health professionals