The CDT threshold set by the prefectural medical commissions remains fixed at strictly less than 1.7%. A result of 1.6% passes, while a result of 1.7% does not. This value reflects regular alcohol consumption over the two to four weeks preceding the sample collection.
We observe that most refusals or postponements in commission are not based on a significantly high CDT, but rather on incomplete files or expired analyses.
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CDT Measurement Method and Inter-Laboratory Variability
Not all laboratories report the CDT in the same way. The method used to quantify desialylated transferrin as a percentage of total transferrin can vary from one establishment to another, which affects the final result.
For a file intended for the prefectural medical commission, we recommend verifying that the chosen laboratory explicitly mentions the measurement method in the report. A result provided without indication of the method may be contested or deemed insufficient by the commission’s physician.
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The CDT rate at the medical commission also depends on factors unrelated to alcohol: certain liver pathologies can skew the result upwards. Reporting these situations to the physician, with supporting medical documents, avoids an unjustified postponement.
Borderline CDT: Securing a Complete File with Gamma GT, VGM, and Psychotechnical Tests
A CDT of 1.5% or 1.6% places the candidate in a gray area. The figure technically falls below the threshold, but the commission may rely on other biological markers to formulate an unfavorable or restricted opinion.
Gamma GT and VGM as Complementary Markers
High gamma GT combined with a borderline CDT is the most common warning signal in commission. Gamma GT increases with chronic alcohol consumption, but also with certain medications, overweight, or hepatic steatosis. An above-normal VGM (mean corpuscular volume) reinforces the suspicion of prolonged consumption.
When the CDT hovers near the threshold, the consistency among these three markers sways the decision. Three normal markers are better than a single passable CDT. If your gamma GT is high for a documented non-alcoholic reason, attaching a letter from the treating physician or specialist changes the interpretation of the assessment.
The Less Than 15-Day Requirement for Analyses
Some prefectures require that biological results be dated less than 15 days at the time of the visit. This constraint is rarely mentioned on general websites, but it leads to concrete postponements. We recommend scheduling the blood test between 10 and 12 days before the commission appointment, to allow the laboratory time to deliver results without exceeding the deadline.
- Check with the prefecture for the exact timeframe required for the validity of analyses (it varies by department).
- Request the laboratory to provide results within 48 to 72 hours, specifying the context of the medical commission.
- Keep a copy of the assessment with the laboratory stamp and the date of collection clearly visible.
Psycho-Technical Tests: A Often Underestimated Prerequisite
For a suspension of six months or more, a cancellation, or an invalidation, psychotechnical tests are required before appearing before the commission. Arriving at the medical appointment without the psychotechnical certificate results in a simple postponement. The test must be conducted at a center approved by the prefecture, and the document must be submitted in original form.
Abstinence and the Kinetics of CDT Decrease Before the Medical Visit
The CDT reflects alcohol consumption over the last two to four weeks. After complete cessation, the rate decreases gradually. A person whose CDT was significantly above the threshold must count on several weeks of complete abstinence before reaching a result compatible with a favorable opinion.
We observe that candidates who plan for at least four to six weeks of abstinence before the blood test achieve more favorable results. Being at 1.2% or 1.3% rather than 1.5% leaves no room for doubt for the commission’s physician.
The most reliable strategy is to conduct a preliminary blood assessment (at their own expense, in a city laboratory) three to four weeks before the official appointment. This “test” assessment allows for checking that the CDT, gamma GT, and VGM are within the acceptable range, and to adjust the schedule if they are not.
After the Favorable Opinion: The Often Forgotten Request on ANTS
The favorable opinion from the medical commission does not automatically restore the license. The candidate must initiate the process of obtaining a new title on the ANTS (National Agency for Secure Titles) website, attaching the medical opinion, the psychotechnical certificate if applicable, and a compliant identity photo.
- Create or update your ANTS account before appearing before the commission to avoid technical delays.
- Scan the medical opinion in high resolution (the document is often stamped and handwritten, low-quality scans are rejected).
- Track the progress of the file online: the processing time varies from a few days to several weeks depending on the prefecture.
A favorable opinion with restrictions (mandatory glasses, time-limited license, EAD requirement) imposes strict adherence to the mentioned conditions. Any deviation observed during a check equates to driving without a valid license.
The medical file to recover a license after an alcohol-related offense hinges on overall consistency: CDT, gamma GT, VGM within the norms, recent analyses, psychotechnical tests completed in advance, and an anticipated ANTS process. Each missing or expired document postpones the return by at least several weeks, the time needed to secure a new slot in the commission.