Intermittent fasting in Type 2 diabetes mellitus and the risk of hypoglycaemia: a randomized controlled trial

Diabet Med. 2018 May;35(5):588-594. doi: 10.1111/dme.13595. Epub 2018 Feb 27.


Aims: To establish whether the risk of hypoglycaemia is greater with 2 consecutive days of very-low-calorie diet compared with 2 non-consecutive days of very-low-calorie diet in people with Type 2 diabetes.

Methods: This was a non-blinded randomized parallel group interventional trial of intermittent fasting in adults. The participants had a BMI of 30-45 kg/m2 , Type 2 diabetes treated with metformin and/or hypoglycaemic medications and an HbA1c concentration of 50-86 mmol/mol (6.7-10%). The participants followed a 2092-2510-kJ diet on 2 days per week for 12 weeks. A total of 41 participants were randomized 1:1 to consecutive (n=19) or non-consecutive (n=22) day fasts, of whom 37 (n=18 and n=19, respectively) were included in the final analysis. The primary outcome was difference in the rate of hypoglycaemia between the two study arms. Secondary outcomes included change in diet, quality of life, weight, lipid, glucose and HbA1c levels, and liver function.

Results: The mean hypoglycaemia rate was 1.4 events over 12 weeks. Fasting increased the rate of hypoglycaemia despite medication reduction (RR 2.05, 95% CI 1.17 to 3.52). There was no difference between fasting on consecutive days and fasting on non-consecutive days (RR 1.54, 95% CI 0.35 to 6.11). Improvements in weight, HbA1c , fasting glucose and quality of life were experienced by participants in both arms.

Conclusions: In individuals with Type 2 diabetes on hypoglycaemic medications, fasting of any type increased the rate of hypoglycaemia. With education and medication reduction, fewer than expected hypoglycaemic events occurred. Although it was not possible to determine whether fasting on consecutive days increased the risk of hypoglycaemia, an acceptable rate was observed in both arms.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Blood Glucose / metabolism
  • Body Weight
  • Caloric Restriction / adverse effects
  • Caloric Restriction / methods*
  • Diabetes Mellitus, Type 2 / complications
  • Diabetes Mellitus, Type 2 / diet therapy*
  • Diabetes Mellitus, Type 2 / drug therapy
  • Fasting*
  • Female
  • Glycated Hemoglobin / metabolism
  • Humans
  • Hypoglycemia / chemically induced
  • Hypoglycemia / epidemiology*
  • Hypoglycemia / etiology
  • Hypoglycemic Agents / administration & dosage
  • Hypoglycemic Agents / adverse effects
  • Male
  • Middle Aged
  • Obesity / complications
  • Obesity / diet therapy*
  • Quality of Life*


  • Blood Glucose
  • Glycated Hemoglobin A
  • Hypoglycemic Agents
  • hemoglobin A1c protein, human