Diabetes screening using home blood glucose meter testing during the Dawn Phenomenon period
The Dawn Phenomenon (DP) was first noted in diabetics as an unexpected increase in blood glucose beginning during sleep early in the morning1. The glucose is derived from increased hepatic gluconeogenesis rather than reduced glucose use and the diabetic state is considered an exaggeration of a natural circadian rhythm2. Non-diabetics exhibit an increase in insulin while remaining normoglycaemic3, but diabetics show little change in insulin secretion(http:// dx.doi.org/10.2337/diacare.7.1.32). This suggests a failure in insulin secretion response to endogenous glucose supply rather than any change in insulin activity itself.
The glucose response period is most commonly from 7 – 9 a.m. The glucose increase in non-diabetics is subtle, up to 0.5 mmol/L (9.9 mg/dL), while for diabetics it is commonly 1 – 5 mmol/L (18 – 90 mg/dL)2, 4. Home blood glucose monitors are precise enough to report a diabetic Dawn Phenomenon pattern. This raises the potential to reduce cost and inconvenience to patients by implementing a self-testing method for routine screening purposes. Two finger-prick tests 1 – 2 hours apart within the 7 – 9 a.m. period are likely to be sufficient, although 3 – 4 tests at half to one hour intervals would be better.