Carnitine deficiencies are rare, even in strict vegetarians, because the body produces carnitine relatively easily.
Rare genetic diseases can cause a carnitine deficiency. Also, deficiencies are occasionally associated with other diseases, such as diabetes and cirrhosis. Among people with diabetes, carnitine deficiency is more likely to be found in persons experiencing complications of diabetes (such as retinopathy, hyperlipidemia, or neuropathy), suggesting that carnitine deficiency may play a role in the development of these complications. A carnitine deficiency can also result from oxygen deprivation which can occur in some heart conditions. In Italy, L-carnitine is prescribed for heart failure, heart arrhythmias, angina, and lack of oxygen to the heart.