Painful peripheral neuropathy is a severe, disabling condition that complicates 10-54% of patients with Type 1 diabetes (1).  Multiple clinical trials have demonstrated that aggressive glycaemic control in patients with diabetes can significantly reduce the incidence and progression of neuropathy (2), however, less is known about the impact of glucose fluctuations on neuropathy.  Studies into the effect of acute hyperglycaemia on pain perception in Type 1 diabetes have been negative (3).

We describe the case of a 37 year old woman with longstanding Type 1 Diabetes (27 years) complicated  by painful lower limb polyneuropathy.  While her HbA1c of 6.8% suggested good glycaemic control, she experienced glucose fluctuations with frequent mild hypoglycaemic events.  Nerve conduction studies revealed mild axonal neuropathy and lower limb arterial duplex ultrasound was normal.    She was a non-smoker, consumed no alcohol and had no exposure to heavy metals.  Results were normal for thyroid function, B12, folate and coeliac antibodies. Trials of multiple antineuritic therapies had been unsuccessful.

The patient opted to change to a low carbohydrate diet (less than 50g per day) and increase her intake of vegetables, protein and saturated fats (dairy, nuts, meat).  Immediately, her basal insulin doses reduced by 30%, and her use of insulin boluses became minimal.  Within two weeks of the dietary changes, hypoglycaemic events were eliminated, and the pain of her peripheral neuropathy improved significantly.  After following this diet for six months, her HbA1c was 6.1%, her weight is unchanged, lipid profile improved, biochemistry was normal and hydroxybutyrate was negative.  Repeat nerve conduction studies are awaited.

This case demonstrates that despite tight glucose control (HbA1c <7%), the patient’s painful peripheral neuropathy persisted likely as a result of glucose fluctuations.  In response to a low carbohydrate diet, the glucose fluctuations resolved, and the patient experienced a significant improvement in pain perception related to peripheral neuropathy. The low carbohydrate diet did not have adverse metabolic consequences.