According to ayurveda, person having more sugar in blood and/or urine are considered as Madhumehi that is the advanced stage of Prameh.
To reverse this condition and to cure this, there are several options available.
1) strict diet regimen
2) simple medicines with precaution of diet
3) panchakarma treatment
4) metallic medicines without precaution of diet
each of these four aims for reversal of the conditions and for cure of the disease.
As per modern science's view to these four ways, these treatments works for a cause to make the body absorb simple carbohydrates like glucose from blood and utilize it for our body. In diabetes, this cycle stops happening on its own by various reasons, leading to high blood and/or urine sugar levels and further leading to diabetic complications.
So, when we control sugar levels, it stables the condition and when we make the body to absorb and utilize the sugar from blood, it reverses the diabetes and at last cures it.