What are capillary blood ketone levels in type 1 diabetic patients using CSII in normal conditions of insulin delivery?

OBJECTIVE: The aim of the study was to determine the normal level of capillary ketonemia in type 1 diabetic patients on continuous subcutaneous insulin infusion (CSII).

RESEARCH DESIGN AND METHODS: A total of 36 type 1 diabetic patients treated by external pump were studied for 2 to 3 weeks. Patients were instructed to self monitor capillary glucose and capillary ketone bodies at least 4 times per day with a handheld Medisense Optium meter and check for urinary ketone bodies in the morning and when blood glucose exceeded 2.5 g/l with a semiquantitative test. Data were collected and analysed for each period of time defined as the time interval between two changes of the infusion site. A period was considered "normal" when no problem causing any impairment in insulin delivery was detected.

RESULTS: 186 periods of 2.1 +/- 0.9 days were recorded; 119 were considered normal. 1281 coupled values of glucose and betahydroxybutyrate were analysed during the so called normal periods. Mean percentage of ketonemia of 0, 0.1, 0.2, > or =0.3 mmole/l were 81.3%, 13%, 3.7% and 2% respectively whereas mean glucose level (g/l) was 1.49 +/- 0.7, 1.48 +/- 0.7, 1.59 +/- 0.8 and 1.89 +/- 0.9 respectively. Only 0.9% of betahydroxybutyrate values were > or =0.3 mmole/l when blood glucose exceeded 2.5 g/l.

CONCLUSION: Our study indicates that ketonemia self monitoring can be a valuable tool to screen insulin deficiency in patients on CSII with a low risk of false positive if we consider a threshold of 0.3 mmole/l for ketone bodies.