Everyone with type 1 diabetes requires injected insulin. Sometimes, however, insulin may not be enough. During puberty, for example, teens with type 1 can become resistant to the effects of insulin. This is thought to be caused by the effects of growth hormone. A study published in Diabetes Care in January 2003 showed that teens with type 1 who were having difficulty with control could benefit from the addition of metformin, an oral agent typically used in type 2 diabetes. The results were positive. Recent research also shows benefits, especially for reducing insulin needs.

So, if your teen is struggling with blood sugar control, you may wish to ask your diabetes team about adding metformin to your diabetes care regimen. It’s not for everyone, but in the right kids, it can make a difference. Although metformin use is off-label in the US for type 1 diabetes (as of 2014), health professionals sometimes prescribe metformin for type 1 diabetes patients in appropriate circumstances. If your teen is struggling with blood sugar control, you may wish to discuss metformin with your diabetes health care team.

More recently, studies are reporting significant benefits from using GLP-1 agonists in type 1 diabetes. These drugs, injected like insulin, are approved in the US only for adults with type 2 diabetes, but their use among adults with type 1 is growing, along with more scientific trials of their use in adults with type 1 diabetes. Examples of these drugs are Victoza and Byetta.

Another new class of drugs for adults with type 2 diabetes is called SGLT-2 inhibitors, where “SGLT” stands for sodium glucose cotransporter. These drugs cause the kidney to excrete glucose at a lower level in the blood, rather than reabsorbing it, resulting in lower blood glucose levels and weight loss. The first drug of this class is called Invokana, but many others are nearing approval and the marketplace.


  1. A Randomized, Double-Blind, Placebo-Controlled Trial of Adjunctive Metformin Therapy in Overweight/Obese Youth with Type 1 Diabetes. Free full text available in HTML and PDF formats.
  2. Effects of low dose metformin in adolescents with type I diabetes mellitus: a randomized, double-blinded placebo-controlled study.
  3. Renal glucose handling in diabetes and sodium glucose cotransporter 2 inhibition. Free full text available in HTML format.
  4. Four weeks of treatment with liraglutide reduces insulin dose without loss of glycemic control in type 1 diabetic patients with and without residual beta-cell function. Free full text available in HTML and PDF formats.
  5. Liraglutide as additional treatment for type 1 diabetes. Free full text available in HTML and PDF formats.
  6. Sodium-Glucose Cotransporter 2 Inhibition and Glycemic Control in Type 1 Diabetes: Results of an 8-Week Open-Label Proof-of-Concept Trial.
  7. Effect of sitagliptin on glucose control in adult patients with Type 1 diabetes: a pilot, double-blind, randomized, crossover trial.
  8. The use of metformin in type 1 diabetes: a systematic review of efficacy.
  9. Metformin added to insulin therapy for type 1 diabetes mellitus in adolescents.
  10. Used of oral antidiabetic agents in pediatric patients – own observations.
  11. Effect of adjunct metformin treatment in patients with type-1 diabetes and persistent inadequate glycaemic control. A randomized study. Free full text available in HTML and PDF formats.
  12. The addition of metformin in type 1 diabetes improves insulin sensitivity, diabetic control, body composition and patient well-being.
  13. The effect of metformin on blood glucose control in overweight patients with Type 1 diabetes.
  14. Usefulness of the addition of metformin to insulin in pediatric patients with type 1 diabetes mellitus [Pediatr Int. 2005 Aug;47(4):430-3]
  15. Metformin as additional therapy in adolescents with poorly controlled type 1 diabetes: randomised placebo-controlled trial with aspects on insulin sensitivity [Eur J Endocrinol. 2003 Oct;149(4):323-9].
  16. Metformin as an adjunct therapy in adolescents with type 1 diabetes and insulin resistance: a randomized controlled trial [Diabetes Care. 2003 Jan;26(1):138-43]. Full text available as HTML or PDF.
  17. The Benefits of Metformin Therapy During Continuous Subcutaneous Insulin Infusion Treatment of Type 1 Diabetic Patients [Diabetes Care 25:2153-2158, 2002]. Full text available as HTML or PDF.
  18. Contraindications to the use of metformin [BMJ 2003;326:4-5 (4 January)]. Full text in PDF format.