Low-calorie and very low-calorie diets are aimed at people with Type 2 diabetes and limit the amount of calories taken daily, sometimes as low as 600 calories per day (the average daily energy requirement is 2000 calories for an adult). A study showed that 3 months after following such a diet for 8 weeks, 2 people out of 3 were still diabetes-free.

The goal is to reduce the amount of fat in the liver and pancreas, which appears to restore blood glucose to normal ranges in just a few weeks.

Pros

• It’s for some an effective method for stopping and reversing Type 2 diabetes in overweight and obese people in a short period of time.
• Can help people to improve their diet in the long term.

Cons

• It’s a drastic diet change that may be hard to follow.
• Can result in side effects as people are not getting enough nutrients.
• Long-term benefits are unknown due to lack of studies.

Source
http://diabetes.webmd.com/news/20110624/very-low-calorie-diet-may-reverse-diabetes
http://www.umm.edu/patiented/articles/what_weight_control_dietary_approaches_type_2_diabetes_000042_4.htm