An increased risk of incident diabetes with statin therapy have been reported in several studies. However, it is not recommended to limit the use of statin for this reason since the absolute risk increase was small, and the cardiovascular event rate reduction with statins overweighed the risk of new diabetes (Scatter N et al. Lancet, 2010). Moreover, each statin may have different effect on the development of incident diabetes. In the West of Scotland Coronary Prevention Study, pravastatin therapy reduced the hazard of becoming diabetic by 30%. Also, with pravastatin use, an increase in adiponectin level, which is related to the improvement in insulin sensitivity, has been reported. In this clinical trial, the investigators are aiming to evaluate the effect of pravastatin on insulin resistance, insulin secretion, glycemic control, and adiponectin level in participants with prediabetes or early diabetes by assigning them in a 24 weeks of pravastatin therapy group or in a placebo group.

Inclusion Criteria:

• Subjects have early diabetes mellitus or prediabetes. Early diabetes mellitus or prediabetes are defined according to the following criteria; Subjects have two or more of the following three, or they have one of them at the initial test and the repeat test.

  1. hemoglobin A1C 5.7-9.0%
  2. fasting plasma glucose level 100mg/dL or more
  3. plasma glucose level 140mg/dL or more at 2 hours after 75g oral glucose tolerance test

• Subjects have one of the following three;

  1. Low-density lipoprotein cholesterol (LDL-cholesterol) 130mg/dL or more, and body mass index (BMI) > 23 kg/m2,
  2. 10 year atherosclerotic cardiovascular disease (ASCVD) risk of 7.5% or more, which is assessed by the ASCVD-Risk-Estimator (Circulation.2014;129:S1-S45)
  3. In diabetic patients, LDL-cholesterol 100mg/dL or more

Exclusion Criteria:

• Hemoglobin A1C > 9.0%
• History of statin use in three months
• Use of oral antidiabetic drugs except for metformin in three months
• History of malignant diseases (cancers)
• History of coronary artery diseases, heart failure, arrhythmia, valvular heart diseases, or cerebrovascular diseases
• Pregnant
• serum creatinine level > 1.5 mg/dL
• aspartate aminotransferase (AST) or alanine aminotransferase (ALT) levels higher than 80 U/l
• Taking weight loss medications, corticosteroids, Angiotensin converting enzyme (ACE) inhibitors, or estrogen replacement therapy
• Chronic hepatitis B or chronic hepatitis C

This study was initially designed as a single center, double-blind, placebo-controlled, 2-group factorial randomized trial (placebo or pravastatin 40mg once daily for 24 weeks). Subjects were randomly assigned, in a 1:1 ratio, to receive pravastatin in a blinded fashion at a dose of 40 mg once daily or placebo. However, because of the problem of expiration date of the placebo drug, the study was converted to an open-label trial, and subjects without any medications were enrolled in an open-label control group in contrast to the pravastatin group. Therefore, the study cohort comprised the pravastatin group, placebo group, and the open-label control group. The placebo group and the open-label control group were classified as the control group.