Yes, Diabetes can be reversed, albeit briefly through some specific interventions.
Diabetes can be broadly classified into Type 1 Diabetes (T1DM) and Type 2 Diabetes (T2DM), although different other types like MODY (maturity onset diabetes in young) and LADA (latent autoimmune diabetes in adults) have been identified lately. I would limit my discussion to the former types.
Type 2 Diabetes can achieve remission in the early stages by incorporating medical nutrition therapy and exercise in our daily routine. Consumption of Mediterranean diet/Dietary approaches to stop hypertension (DASH) diet along with 150 min per week of moderate intensity structured physical activity can lead to partial reversal of Type 2 Diabetes.
Bariatric surgery (done for morbid obesity) can revert back Type 2 Diabetes in 23-60% of cases depending on the baseline duration and severity of diabetes. However, it might not be effective in advanced stages of Type 2 Diabetes and chance of recurrence is substantial in the long-term who initially respond.
On the other hand, Type 1 Diabetes can only be reversed by successful SPK (simultaneous pancreas and kidney transplantation –done in handful of centres in India) or Islet transplantation (even rarely performed).
Drug or stress induced hyperglycemia wanes off in most cases if inciting entity vanishes.