You might be aware that as a metabolic disorder, some forms of diabetes come with excessive weight. But diabetes might also cause a sudden drop in weight too. In fact, many patients who are ultimately diagnosed with diabetes first go to their doctor with concerns about unexplained weight loss. Several mechanisms are behind this symptom. Weight loss can occur as a consequence of high blood sugar, dehydration, muscle breakdown and problems with your thyroid.
High Blood Sugar
Although both type 1 and type 2 diabetes can involve fairly dramatic weight loss over several days at the onset of the disease, it tends to be more common among people with type 1. In both cases, the cause is that your body fails to adequately deal with insulin. The job of insulin is to transport glucose from the foods you eat into your cells to provide energy for all the work that’s required to keep you alive. However, most type 1 diabetics don’t produce insulin. Type 2 diabetics either don’t produce enough insulin or their bodies don’t respond to it properly. Consequently, even if you eat normally, that blood sugar simply builds up and gets excreted in your urine. This causes weight loss, but it could also damage your organs if you don't receive treatment. If you experience an unexplained weight loss, surpassing 5 percent of your body weight within days, see your health care provider as soon as possible.
Another symptom of diabetes associated with weight loss is frequent urination. When you urinate more frequently and don’t drink enough to replace the lost fluid, you become dehydrated. Urination increases in diabetes, because your kidneys have to work harder to filter the excess glucose building up in your system. The increased glucose in the urine draws fluid from your tissues. When you lose glucose through your urine, you're also losing calories. This, as well as dehydration, can lead to rapid weight loss.
Poorly controlled diabetes can cause weight loss through muscle wasting, according to a report published in the “British Medical Journal.” Scientists in this study found that the insulin deficiency found in diabetes both decreases muscle synthesis and increases its breakdown. In a later meta-analysis published in the “Journal of Nutrition,” these findings were confirmed, with the report saying that insulin replacement helps diminish this effect of the disease. However, as muscle makes up up to 36 percent of an average woman’s weight and up to 45 percent of a man’s weight, muscle wasting can lead to weight loss through diabetes.
People with diabetes have a higher prevalence of thyroid disorders than people without diabetes, according to Dr. Patricia Wu. The thyroid is a hormone-producing gland inside your neck that sits above your collarbone, just underneath your skin. The thyroid helps set your metabolic rate. With hyperthyroidism, the glands makes too much hormone and causes weight loss. Wu explains that this dysfunction can worsen blood sugar control and require that you take more insulin. It also makes your liver produce more blood sugar and is linked to greater insulin resistance. In fact, says Wu, excessive amounts of thyroid hormone in the bloodstream might reveal latent diabetes. A major sign of hyperthyroidism is weight loss. It also speeds up your heart rate and causes sweating and tremors, symptoms that look a lot like low blood sugar. Your health care provider will advise you on how to monitor your blood sugar to understand the effects of hyperthyroidism and blood sugar fluctuations.
- "Clinical Diabetes"; "Thyroid Disease and Diabetes"; Patricia Wu; Winter 2000
- American Diabetes Association: Symptoms
- "Journal of Nutrition"; Protein Metabolism in Insulin-Dependent Diabetes Mellitus
- “British Medical Journal"; "Clinical Usefulness of Urinary 3-methylhistidine Excretion in Indicating Muscle Protein Breakdown"; M. Elia et al; January 31, 1981