Insulin vs. Metformin Treatment

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Diabetes affected 7.8 percent of the American population in 2007. Diabetes has several causes. Type 1 diabetes, previously called juvenile diabetes, caused by failure of the pancreas to produce insulin, affects 5 percent to 10 percent of people with diabetes, while Type 2 diabetes, previously called adult-onset diabetes, accounts for most of the rest, according to the National Institute of Diabetes and Digestive and Kidney Disorders. Different drugs are used to treat diabetes, depending on the cause and severity of the disease. Insulin, an injectable medication, and metformin, an oral medication, have different actions.


The purpose of both insulin and metformin is to lower blood glucose levels. Insulin injections replace the insulin your body can no longer make when the cells in the pancreas cease to function. Metformin is an oral hypoglycemic, which lowers blood glucose levels by decreasing the liver’s output of glucose. Metformin also increases insulin sensitivity, and improves not only blood glucose levels but also lipid levels and often results in weight loss. Of all diabetics, 14 percent take insulin only, 57 percent take oral medications only and 14 percent take a combination of both, the NIDDK reports.


Oral hypoglycemics are used only in Type 2 diabetes, because Type 1 diabetics make little or no insulin, so reducing the glucose levels produced by the liver won’t reduce blood glucose levels. Without insulin, glucose can’t enter cells and remains in the bloodstream. While all Type 1 diabetics take insulin, some Type 2 diabetics also need insulin in addition or instead of oral hypoglycemics such as metformin. Insulin, which must be injected, comes in several forms and doses, and can have rapid or slow onset.

Side Effects

Diarrhea, the most common side effect of metformin, improves if metformin is taken with food. Liver failure and increased acidity, acidosis, occur rarely, The Merck Manuals Online Medical Library states. Insulin must be carefully calibrated or blood glucose levels may drop too low, a condition called hypoglycemia. Taking insulin without eating or taking too much insulin for the amount of food eaten can cause hypoglycemia. Symptoms of hypoglycemia include weakness, shakiness, sweating, lightheadedness and confusion; coma and death can result in severe cases.


Both metformin and insulin help to normalize blood glucose levels. Keeping blood glucose levels as close to normal levels as possible limits the damage high blood glucose imposes on every blood vessel and organ of the body. High blood glucose levels lead to poor circulation, heart problems, vision problems, nerve damage, susceptibility to infection and kidney damage. While damage occurs earlier in Type 1 diabetics, Type 2 diabetics can also experience complications.


For Type 1 diabetics, insulin is the only medication choice. For Type 2 diabetics, medical practitioners generally start with an oral hypoglycemic such as metformin and add insulin only when oral hypoglycemics can’t stabilize blood glucose levels.