Any blood sugar level under 600 milligrams is usually considered safe.
But if your blood sugar level gets to or tops 600 milligrams per deciliter (mg/dL), or 33.3 millimoles per liter (mmol/L) then the blood sugar level is becoming dangerous and you need to get the blood sugar level lowered.
If you cannot get the blood sugar level lowered at home you need to seek medical treatment.
Adding a Spoonful or two spoonfuls of cinnamon to some warm tea can help lower your blood sugar levels naturally but if you can't get your blood sugar levels lowered down to where they should be or the blood sugar level stays too high then you need to seek medical attention.