A glucose level of 11.1 mmol/L or more in the blood sample taken after two hours indicates that you have diabetes. The answer to your question is 20 mmol/ glucose per litre of blood. The 'normal' sugar level ideally should be around 4-8ish. Sugar levels at 20 will make you very tired. Not sure what you mean by 100's but USA sugar readings are different to UK. For instance 20 in UK is 360 in USA. My sugar levels vary between 3-33. Prolonged high sugar will result in neuropathy (starts by tingling in big toe, spreading to losing feeling in whole foot) so try to keep sugar level as low as possible.