Ambulatory 24-hour fast using flexible insulin therapy in patients with type 1 diabetes.

Aim: Prolonged fasting may be necessary in life for religious, medical and other reasons. For this reason, our study investigated the feasibility and safety of a 24-h fast conducted at home for patients with type 1 diabetes.

Research Design And Methods: Thirty-four patients with type 1 diabetes performed a 24-h complete fast at home. Thirteen patients were treated with multiple insulin injections using either glargine (n=12) or NPH (n=1) as basal insulin. The remaining patients were treated with an insulin pump. All patients received their basal insulin only, which was adjusted to 40% of their total daily dose, and were monitored by either a Gold(®) or Guardian(®) continuous glucose monitoring (CGMS) device. Capillary glucose (SMBG) was targeted at 3.9-7.8 mmol/L, with a standardized protocol for correction of hyper- and hypoglycaemia. Interstitial glucose (IG) profiles were compared with the SMBG values; the IG profiles of patients using glargine or a pump and either of the two CGMS devices were also compared.

Results: All of the patients completed the 24-h fast with no major incident. At the end of the fast, 80% of the IG values were on target. The route by which insulin was delivered made no difference, but there were more IG values on target in patients monitored by the Guardian(®) device. IG was below target in 104 occurrences and above-target in 34. After a mean intake of 10 g of sucrose, below-target IG was corrected within 30 min [range: 15-40]. The mean insulin dose to correct above-target episodes was 1 U.

Conclusion: Prolonged fasting is possible at home in patients with type 1 diabetes, provided the basal dose is adjusted. The use of CGMS is not necessary, but offers useful information on the patient's IG profile during the fast.