diff --git a/src/app/api/cron/garmin-sync/route.ts b/src/app/api/cron/garmin-sync/route.ts
index 59ee4e4..e2e7933 100644
--- a/src/app/api/cron/garmin-sync/route.ts
+++ b/src/app/api/cron/garmin-sync/route.ts
@@ -206,12 +206,12 @@ export async function POST(request: Request) {
         user.activeOverrides,
       );
 
-      // Create DailyLog entry
+      // Upsert DailyLog entry - update existing record for today or create new one
       // Store default value 100 for body battery when Garmin returns null.
       // This prevents PocketBase's number field null-to-0 coercion from
       // causing the dashboard to display 0 instead of a meaningful value.
       // Use YYYY-MM-DD format for PocketBase date field compatibility
-      await pb.collection("dailyLogs").create({
+      const dailyLogData = {
         user: user.id,
         date: today,
         cycleDay,
@@ -225,7 +225,18 @@ export async function POST(request: Request) {
         trainingDecision: decision.status,
         decisionReason: decision.reason,
         notificationSentAt: null,
-      });
+      };
+
+      // Check if record already exists for this user today
+      try {
+        const existing = await pb
+          .collection("dailyLogs")
+          .getFirstListItem(`user="${user.id}" && date="${today}"`);
+        await pb.collection("dailyLogs").update(existing.id, dailyLogData);
+      } catch {
+        // No existing record - create new one
+        await pb.collection("dailyLogs").create(dailyLogData);
+      }
 
       // Log sync complete with metrics
       const userSyncDuration = Date.now() - userSyncStartTime;