There are two old drugs that have been found to lower the blood glucose when they were used for other purposes. The following information describes their properties. Discuss them with your doctor if you need a bit more control of your blood glucose.
Bile acid sequestrants
Bile acid sequestrants are drugs that are used to reduce the total cholesterol and the LDL (bad) cholesterol. When they were being used for that purpose it was noted that they also lowered the blood glucose and the hemoglobin A1c. Although the lowering of hemoglobin A1c is modest, about 0.5 percent, these drugs may have a place in prediabetes or mild type 2 diabetes. They do not cause hypoglycemia.
The FDA has authorized the use of colesevalam (brand name Welchol) for this treatment. It can be used for both type 1 and type 2 diabetes. Side effects include constipation and nausea. Colesevelam comes as 625 mg tablets as well as 1875 and 3750 mg powder packets. The dose is 3750 mg once daily. It may be used alone or with other oral hypoglycemic agents and does not cause weight gain.
Bromocriptine is another drug long used for a different indication that has been found to have glucose-lowering effects. It has been used to treat brain tumors that produce too much growth hormone or prolactin. It was discovered to lower the blood glucose and the hemoglobin A1c to a slightly greater extent (hemoglobin A1c reduced 0.6-0.7 %) then the bile acid sequestrants but by a different mechanism. It also reduces triglycerides and free fatty acids, without causing hypoglycemia or weight gain.
Side effects include nausea, dizziness and headache in less than 15 percent of patients. The dose of Bromocriptine (called Cycloset) is 1 0.8 mg tablet increased by 1 tablet per week up to a maximum of 4.8 mg. It may be used by itself or with other oral agents.