Carsten,

In our hands, overnight fasted mice run a little lower than rats, the range being 65-90mg/dl and 85-100 mg/dl respectively.

In case of mice and young rats, we tend to avoid overnight fasting and usually use only 4-6 hr fasting.

Blood glucose levels in rodents fed ad libitum, vary a little depending on the time of measurements. On an average, you can add ~10-15mg/dl to the fasting values.

We have noted more intra-personnel variations in blood glucose levels than inter-animal differences. This is quite predictable effect and as the researchers gain experience in handling animals and feel comfortable, they tend to get the animals less excited, which is reflected in their blood glucose levels. Generally speaking, if a normal rodent gives you a blood glucose value >120mg/dl, you should conclude that its the person who needs a little more training. 

[How exciting, I have a brave voiceless admirer!  ;)  ]

hi Carsten,

from our experience, we draw normal "human" blood sugar values (between 4.44 - 6.66 mmol/l.) to our lab rats ( SD, WKY, and DIO Model). fasting blood glucose levels in awake rat ( anesthesia causes slight hyperglycaemia) range 117.06±1.96 mg/dl.  but then again we establish the mean value for our control group for each time we pilot an experiment.

may I suggest :

http://www.madsci.org/posts/archives/2001-02/982242802.Zo.r.html     and 

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3809632/      

hope it is what you are looking for. Best wishes .

I have done lots of GTTs on mice and they are extremely variable. Fasting glucose levels are anywhere from 50-150 depending on the length of the fast (6h-36h), and after glucose injection they spike to 300-600 sometimes. For a more predictable baseline, I usually fast overnight, starting just before lights out, then measure first thing in the morning.

Carsten,

In our hands, overnight fasted mice run a little lower than rats, the range being 65-90mg/dl and 85-100 mg/dl respectively.

In case of mice and young rats, we tend to avoid overnight fasting and usually use only 4-6 hr fasting.

Blood glucose levels in rodents fed ad libitum, vary a little depending on the time of measurements. On an average, you can add ~10-15mg/dl to the fasting values.

We have noted more intra-personnel variations in blood glucose levels than inter-animal differences. This is quite predictable effect and as the researchers gain experience in handling animals and feel comfortable, they tend to get the animals less excited, which is reflected in their blood glucose levels. Generally speaking, if a normal rodent gives you a blood glucose value >120mg/dl, you should conclude that its the person who needs a little more training. 

[How exciting, I have a brave voiceless admirer!  ;)  ]

My data on overnight fasted (18-19 hrs) C59BL/6J showed pretty consistent glucose levels of 92-125 mg/dl (on average of 117 mg/dl) measured with glucometer from cheek blood. We were very careful with the stress.

In unstressed mice (DIO, C57BL6/BomTac) plasma glucose variations are observed. The animals are extremely sensitive to noise in stables and stress from handling. The problem with glucometers is that it is a 1 point measurement in time. I have enclosed data from DSI continuous telemetric glucose measurements. Here you can observe large fluctuations during a day. The example includes an IPGTT (1 mg/g BW).

The example animal has blood glucose values btw 90-170 mg/dL unfasted values (DIO animal, 45 g BW). The largest variations are at night (where 80% of daily food intake is ingested).

Telemetric solution allows for second resolution measurements of blood glucose (unstressed/unhandled animal).

We have published in 1995 the paper: Journal of Physiology (1995), 486.1, pp.223-228 showing intracellular recordings in pancreatic B-cells in in vivo anesthesized mice. Previously to the surgical process the animals were allowed ad libitum access to food and water. After the initiation of the surgical (anesthesia) process could take 2-3 hours up to the recording and measuring glycemia from portal vein samples. Then, the process would imply 2-3 hours fasting plus stress. In this condition the glycemic basal levels ranged (measured with a glycometer) from 7-8 mM (126-145 mg/dl).

Sorry, I've wrote "portal" and it was a mistake. The samples were obtained form the cava vein.