Association Between Glycaemic Control and the Intake of Thiazide Diuretics, Beta Blockers and Levothyroxine in People Without Diabetes

Abstract

Abstract Objective The pharmacological additional information for many medications includes warnings stating that the blood sugar control may be worsened by the intake of certain drugs. However a quantification of the effects is missing. This may result in confusion for patients as well as for their physicians. The aim of this study was to assess a potential association between medication (beta blockers, thiazides, levothyroxine) and HbA1c in people without diabetes. Methods In this cross-sectional study we analysed data from 2 921 people (7 699 visits) without diabetes (age 46.6 y; 69.1% women; BMI 27.6±6.4 kg/m²; HbA1c 5.2%) who had at least one HbA1c determination and a complete documentation of their drug intake. An oral glucose tolerance test was not performed. The participants were divided in 8 groups (no regular drug intake, levothyroxine alone, beta blockers alone, thiazides alone, combination 2 of 3, combination of all 3). Patients with known distorting influences of the HbA1c were excluded. Results People with no regular drug intake had an HbA1c of 5.4% [35.8 mmol/mol]. The HbA1c of the group that took all 3 drugs in combination was 5.6% [38.2 mmol/mol]. A multiple linear mixed model showed an increase in HbA1c for thiazides (β=0.0558, p=0.025) and a decrease for combination of levothyroxine and thiazide (β=−0.0765, p=0.010). Conclusion Thiazides and the combination of levothyroxine and thiazides were associated with slight changes in HbA1c. In this study there was no association between the intake of beta blockers and HbA1c. At least for people without diabetes these effects seem to be of minor importance.