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Metformin vs. Januvia for Weight Loss

Marketed as treatment options for patients diagnosed with Type 2 diabetes and insulin resistance, Metformin and Januvia work in the body similarly by controlling your blood glucose levels and by helping your body better use its own insulin. Metformin is the drug name for Glucophage, produced and sold by Bristol-Myers Squibb. Sitagliptin is the drug name for Januvia, produced and sold by Merck Pharmaceuticals. Obesity and lack of physical activity can contribute to insulin resistance. Reduction of insulin resistance has benefits that can lead to reduced hunger and weight loss.

Glucose and Insulin

The primary source of energy for the human body is glucose. Food that you eat is turned into glucose, also called blood sugar. When the amount of sugar in your blood rises, your pancreas makes insulin to help your cells be able to use the glucose. When insulin levels rise, excess glucose in your bloodstream will be stored as body fat. According to Mayo Clinic, insulin and weight gain often go hand in hand. With drug therapy, insulin levels can be normalized, possibly halting weight gain.

Insulin Resistance

The National Institutes of Health states that insulin resistance is a condition in which the body produces insulin but does not use it properly. If you are insulin resistant, your muscle, fat and liver cells do not respond properly to insulin. As a result, your body needs more insulin to help glucose enter cells. This increase in insulin often causes people who are insulin resistant to put on extra pounds since more glucose can be stored.


The National Institutes of Health’s Medline Drug Library declares that metformin helps to control the amount of blood sugar in your blood 3. It decreases the amount of glucose you absorb from your food and the amount of glucose made by your liver. Metformin also improves your body's response to insulin.


Januvia, or sitagliptin, is classified as a DPP-4 inhibitor, making it a bit different than metformin. Essentially, Januvia accomplishes the same thing as metformin by lowering blood sugar and improving your body’s response to insulin.


According to a study published by the American Journal of Psychiatry, metformin, which is prescribed for patients with non-insulin-dependent diabetes to control blood sugar levels, has been reported to effect weight loss in several groups of patients characterized by insulin resistance. The National Institutes of Health says that Januvia, or sitagliptin, stimulates insulin secretion when high blood sugar is present and inhibits glucagon secretion 1. However, in clinical studies it is weight neutral. Based on scientific studies, metformin has greater weight-loss potential.