Approximately 90% of people with type 2 diabetes have overweight or obesity (by BMI criteria), and many people with type 1 diabetes struggle with excess weight as well.  Studies of lifestyle approaches to weight management, as well as studies of weight loss medications (conducted in people with type 2 diabetes), consistently show that people with diabetes have a harder time losing weight than people that do not have diabetes.   Why?


1. For people with type 2 diabetes, some medications that control blood sugar can cause weight gain, including insulin, sulfonyureas (eg gliclazide (Diamicron), glyburide), meglitinides (eg repaglinide (Gluconorm)), and thiazolidinediones (eg pioglitazone (Actos)) .  Often, medications that control blood sugars but which cause weight loss (specifically, GLP1 receptor agonists and SGLT2 inhibitors) or are weight neutral (metformin, DPP4 inhibitors) can be added or substituted for a more favorable effect on weight.


While people with type 1 diabetes need insulin, sometimes other medications that have been approved for type 2 diabetes can be included in the treatment regimen to help people with type 1 diabetes and obesity improve weight and/or reduce insulin needs (this would be considered ‘off label’ use, and is something that needs to be discussed and considered carefully between the patient and their doctor).


2.  Stopping loss of sugar in the urine with treatment. If a person has very high sugars (over 15 mmol/L), the sugar overflows into the urine.  When sugars come under control, the sugar stops overflowing into the urine and these calories are stored in the body instead (usually converted to fat), which contributes to weight gain.   People with poor control of their diabetes also have increased protein turnover, requiring increased protein synthesis, which burns more energy.  Note that these are not reasons to allow diabetes to run out of control – poorly controlled diabetes is dangerous as it can lead to metabolic decompensation, and over time, it increases the risk of diabetes-related complications (eg to eyes, heart, kidneys, nerves and so on).


3. Low blood sugars (hypoglycemia). The treatment of low sugars includes eating sugar/carbs to raise the blood sugar, which adds extra calories. If a person with diabetes has had a low blood sugar in the past, it can be very frightening, and fear of this happening again can result in compensatory overeating to avoid having a low again.


4.  Stress. Many people who have diabetes find it stressful to manage this condition.  We know that stress can increase appetite and lead to emotional eating.


5.  Part of diabetes treatment is learning about healthy eating habits , with a focus on carbohydrate intake.  Sometimes, this necessary focus on food intake can result in an unhealthy relationship with food.  We can see this in a wide variety of age groups, but this may be at a higher risk of happening for people diagnosed with diabetes in childhood or young adulthood.


6. Complications of diabetes can limit physical activity.  This could include heart disease, foot ulcers, and nerve damage to the lower extremities.


7.  Insulin resistance in type 2 diabetes (or people with type 1 diabetes and overweight/obesity) is often cited as a reason for weight loss being more difficult, but how this actually works is poorly understood.


Weight management is important to many people who have diabetes.  As health care providers, it’s important to explore potential contributors to each patient’s weight struggle, and to do everything we can to:

  • Optimize diabetes medications.  For people with type 2 diabetes, the 2020 Diabetes Canada guidelines recommend consideration of GLP1 receptor agonists or SGLT2 inhibitors if weight reduction is a priority.
  • Help our patients avoid low blood sugars (optimize medications; use glucose monitoring strategies that can help identify lows).
  • Find ways to help patients be active in the context of other health issues.
  • Help our patients cultivate a healthy relationship with food.
  • Help with emotional/psychological support to navigate stress related to managing diabetes.
  • Consider whether other non-diabetes medications each person is taking may be contributing to weight gain, and whether there are alternatives that could be used instead (see Table 8).
  • Consider weight management medication for improvement in weight and diabetes control.


Disclaimer: I receive honoraria as a continuing medical education speaker and consultant from the makers of SGLT2 inhibitors and GLP1 receptor agonists. I have been involved as an investigator in clinical trials of GLP1 receptor agonists and SGLT2 inhibitors.


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